全文获取类型
收费全文 | 23133篇 |
免费 | 1155篇 |
国内免费 | 255篇 |
专业分类
耳鼻咽喉 | 254篇 |
儿科学 | 485篇 |
妇产科学 | 671篇 |
基础医学 | 2617篇 |
口腔科学 | 529篇 |
临床医学 | 1701篇 |
内科学 | 6227篇 |
皮肤病学 | 397篇 |
神经病学 | 2479篇 |
特种医学 | 903篇 |
外科学 | 3648篇 |
综合类 | 45篇 |
一般理论 | 4篇 |
预防医学 | 933篇 |
眼科学 | 282篇 |
药学 | 1354篇 |
中国医学 | 48篇 |
肿瘤学 | 1966篇 |
出版年
2024年 | 23篇 |
2023年 | 184篇 |
2022年 | 400篇 |
2021年 | 710篇 |
2020年 | 441篇 |
2019年 | 526篇 |
2018年 | 691篇 |
2017年 | 558篇 |
2016年 | 641篇 |
2015年 | 717篇 |
2014年 | 934篇 |
2013年 | 1121篇 |
2012年 | 1774篇 |
2011年 | 1805篇 |
2010年 | 1014篇 |
2009年 | 1002篇 |
2008年 | 1632篇 |
2007年 | 1608篇 |
2006年 | 1459篇 |
2005年 | 1390篇 |
2004年 | 1360篇 |
2003年 | 1218篇 |
2002年 | 1076篇 |
2001年 | 156篇 |
2000年 | 125篇 |
1999年 | 171篇 |
1998年 | 188篇 |
1997年 | 166篇 |
1996年 | 167篇 |
1995年 | 128篇 |
1994年 | 87篇 |
1993年 | 96篇 |
1992年 | 98篇 |
1991年 | 75篇 |
1990年 | 68篇 |
1989年 | 82篇 |
1988年 | 54篇 |
1987年 | 72篇 |
1986年 | 59篇 |
1985年 | 40篇 |
1984年 | 61篇 |
1983年 | 51篇 |
1982年 | 38篇 |
1981年 | 41篇 |
1980年 | 43篇 |
1979年 | 19篇 |
1978年 | 15篇 |
1977年 | 23篇 |
1976年 | 15篇 |
1974年 | 14篇 |
排序方式: 共有10000条查询结果,搜索用时 13 毫秒
71.
The long pentraxin PTX3 up-regulates tissue factor in activated monocytes: another link between inflammation and clotting activation 总被引:4,自引:0,他引:4
Napoleone E di Santo A Peri G Mantovani A de Gaetano G Donati MB Lorenzet R 《Journal of leukocyte biology》2004,76(1):203-209
Pentraxin-3 (PTX3), an acute-phase protein that belongs to the family of the PTXs, is found elevated in septic shock and increased in patients with acute myocardial infarction. As tissue factor (TF) plays a key role in thrombosis and inflammation associated with atherosclerosis and as we have recently reported that PTX3 increases TF synthesis in endothelial cells, we tested whether PTX3 could modulate TF expression in monocytes. Monocytes from peripheral blood of healthy donors were incubated with highly purified PTX3 with or without lipopolysaccharide (LPS). Cells were then disrupted, and procoagulant activity was assessed by a one-stage clotting time. PTX3 enhanced TF activity and antigen from LPS-stimulated monocytes in a dose-dependent way. The effect was specific, as other PTXs, such as C-reactive protein and serum amyloid P component, were ineffective. Moreover, the increase in activity was specific for LPS, as in the presence of other TF-inducing agents such as interleukin-1beta and tumor necrosis factor alpha, PTX3 was not effective. The increase in TF activity requires mRNA synthesis, as assessed by polymerase chain reaction. The mechanism by which PTX3 modulates TF synthesis resides in an enhanced IkappaB, alpha phosphorylation and degradation and increased migration of the transacting factor c-Rel/p65 into the nucleus, as determined by Western blot and electro-mobility shift assay. These results show that PTX3 is an enhancer of the expression of TF by mononuclear cells. In the area of vascular injury, during the inflammatory response, cell-mediated fibrin deposition takes place. PTX3 increases TF expression, thus potentially playing a role in thrombogenesis and wound healing. 相似文献
72.
Early detection of negative BACTEC MGIT 960 cultures by PCR-reverse cross-blot hybridization assay 下载免费PDF全文
Romano L Sanguinetti M Posteraro B Ardito F Gesu G Schito AM Fadda G 《Journal of clinical microbiology》2002,40(9):3499-3501
We evaluated the efficacy of a PCR-reverse cross-blot hybridization assay, a test which permits identification of mycobacteria by means of species-specific probes and a Mycobacterium-specific probe, for early detection of negative BACTEC MGIT 960 mycobacterial cultures. Aliquots of 549 cultures were collected 7 days after the culture media were inoculated with various clinical specimens and tested with the molecular assay. PCR results were compared to those obtained at the end times with the BACTEC MGIT 960 system. Of the 549 specimens analyzed, 484 were found to be negative and 64 were found positive by both methods; one specimen, found to be positive by the BACTEC MGIT 960 system, was identified as negative by the molecular assay. In view of its high negative predictive value (99.8%), the PCR-reverse cross-blot hybridization assay appears to be a valid tool for early detection of negative BACTEC MGIT 960 cultures. 相似文献
73.
Paromomycin and Geneticin Inhibit Intracellular Cryptosporidium parvum without Trafficking through the Host Cell Cytoplasm: Implications for Drug Delivery 下载免费PDF全文
Jeffrey K. Griffiths Ramaswamy Balakrishnan Giovanni Widmer Saul Tzipori 《Infection and immunity》1998,66(8):3874-3883
Cryptosporidium parvum, which causes intractable diarrhea and lethal wasting in people with AIDS, occupies an unusual intracellular but extracytoplasmic niche. No reliable therapy for cryptosporidiosis exists, though the aminoglycoside paromomycin is somewhat effective. We report that paromomycin and the related compound geneticin manifest their major in vitro anti-C. parvum activity against intracellular parasites via a mechanism that does not require drug trafficking through the host cell cytoplasm. We used both normal and transformed aminoglycoside-resistant Caco-2 or MDBK cells in these studies. Timed-exposure experiments demonstrated that these drugs inhibit intracellular but not extracellular parasites. Apical but not basolateral exposure of infected cells to these drugs led to very significant parasite inhibition, indicating an apical topological restriction of action. We estimated intracytoplasmic concentrations of paromomycin, using an intracellular bacterial killing assay, and found that C. parvum infection did not lead to increased paromomycin concentrations compared to those in uninfected cells. Global [3H]paromomycin uptake by Caco-2 cells was ~200-fold higher than the estimated intracytoplasmic paromomycin concentration, suggestive of host cell vesicular uptake and concentration (as has been reported with other cell lines). However, preinfection exposure of Caco-2 cells to paromomycin did not result in subsequent inhibition of parasite development, indicating that if exogenous paromomycin enters the infected host cell vesicular compartment, it does not effectively communicate with the parasite. Thus, the apical membranes overlying the parasite and parasitophorous vacuole may be the unsuspected major route of entry for paromomycin and may be of importance in the design and discovery of novel drug therapies for the otherwise untreatable C. parvum. 相似文献
74.
Jeannin P Magistrelli G Herbault N Goetsch L Godefroy S Charbonnier P Gonzalez A Delneste Y 《European journal of immunology》2003,33(2):326-333
Outer membrane protein A (OmpA) is a class of bacterial cell wall protein that is immunogenic without adjuvant. As specific immune responses are initiated in the lymph nodes (LN, we analyzed the effect of the OmpA from Klebsiella pneumoniae (KpOmpA) onchemokine/ chemokine receptor expression by APC and on cell migration to the LN. Upon contact with KpOmpA, human immature DC and macrophages acquire CCR7 expression and responsiveness to CCL21. In parallel, CCR1 and CCR5 expression is down-regulated and CXCL8, CCL2, CCL3 and CCL5 production is up-regulated. Mice injected subcutaneously with KpOmpA present a transient inflammatory reaction at the site of injection accompanied by an enlargement of the draining LN with a higher proportion of DC and macrophages. Lastly, when exposed to KpOmpA prior injection, DC but not macrophages migrate to the draining LN. In conclusion, KpOmpA confers a migratory phenotype to DC and triggers their migration to the regional LN. This property contributes to explain how innate cells initiate adaptive immune response upon recognition of conserved bacterial components and also why OmpA is immunogenic in the absence of adjuvant. 相似文献
75.
P. Nanni M. P. Colombo C. De Giovanni P.-L. Lollini G. Nicoletti G. Parmiani G. Prodi 《International journal of immunogenetics》1983,10(5):361-370
We studied the expression of H-2b alloantigens in three different B16 melanoma lines cultured in vitro, Cell lines were B16-F1 and two cell cultures (named B16-A and B16-B) newly derived from two different in vivo sublines of B16 melanoma. The assays used were in vivo tumour growth in allogeneic (BALB/c and B10.BR) as compared to syngeneic mice, in vitro cell-mediated cytotoxicity by anti-H-2b immune lymphocytes and absorption of anti-H-2b antisera activity. The B16-F1 line was able to efficiently kill allogeneic hosts, could not be lysed by anti-H-2b cytotoxic effectors and did not express any serologically detectable amount of H-2b alloantigens. The B16-A line was H-2 positive during the early in vitro passages, then, at the 8th–10th passages, it acquired the capacity to kill allogeneic hosts, lost the sensitivity to anti-H-2b cytotoxic effectors and the H-2Kb antigens became undetectable. The expression of H-2Db was reduced, although at a lower degree. Similar data were obtained with B 16-B cells, which after 10 in vitro passages grew and killed allogeneic hosts, showed a decreased sensitivity to cytotoxic anti-H-2b effectors and a very low expression of the K region antigens. The results indicate that H-2 expression is altered in B 16 melanoma lines and this may influence the different metastatic capacity of such cells. 相似文献
76.
Giovanni Perego Gabriele Lugli Ugo Pedretti Giuseppe Allegra 《Macromolecular chemistry and physics.》1988,189(11):2687-2701
The crystal structure of iodine/trans-polyacetylene complexes (CHIy)x (y = 0,009, 0,035, 0,17 and 0,30) was investigated by X-ray diffraction analysis of highly oriented samples. An iodine-containing phase (PAI) was observed in all cases, accompanied by residual crystallinity due to pristine polyacetylene (PA) for y < 0,17. A structural model is proposed for PAI, consisting of blocks of iodine-saturated PA (PAIs) and blocks of PA, arranged in a mosaic-like lattice, paracrystalline in character. PAIs, corresponding to (CHI0,40)x, is formed by layers of (CH)x chains alternating with layers containing polyiodide chains, the latter being characterized by ordered stacking of sequentially disordered (I3?-I5?-I3?) groups. I… C non-bonded interactions are identified in the lattice, which may be responsible for the electron transfer from the polymer to the polyiodide anions. Short-range transverse correlation occurs within the polyiodide layers with a resulting quasi-regular two-dimensional lattice of iodines. The iodine and the polymer lattices are incommensurate along c. The model fits the experimental data from an X-ray fibre diagram. A mathematical expression is derived, which allows to evaluate the intensity scattered by the iodine lattice. An approximate expression of the non-equatorial intensity along the ξ reciprocal direction was obtained, which accounts for the modulation of the streaks observed in the fibre pattern. 相似文献
77.
Guido Martignoni Maurizio Pea Matteo Brunelli Marco Chilosi Alberto Zamó Manuela Bertaso Paolo Cossu-Rocca John N Eble Gregor Mikuz Giacomo Puppa Cecile Badoual Vincenzo Ficarra Giovanni Novella Franco Bonetti 《Modern pathology》2004,17(12):1455-1463
CD10 has been considered a useful marker in the diagnosis of renal carcinomas, because of its expression in clear cell and papillary renal cell carcinomas and its absence in chromophobe renal cell carcinomas. On the other hand, chromophobe renal cell carcinoma expresses parvalbumin, which is absent in clear cell and papillary renal cell carcinomas. To further address the relevance of these markers, we studied the expression of CD10 and parvalbumin in 42 samples of chromophobe renal cell carcinoma (seven of which had aggressive features, including invasion beyond the renal capsule, renal vein invasion, metastases, or sarcomatoid transformation), 75 clear cell renal cell carcinomas (eight metastatic) and 51 papillary renal cell carcinomas (two metastatic). CD10 was found in 100% of clear cell renal cell carcinomas, 63% of papillary renal cell carcinomas and in all metastatic cases of both types. At variance with previous studies, we found CD10 expression in from 30 to 90% of the neoplastic cells, in 11 of 42 (26%) chromophobe renal cell carcinomas. The CD10-positive cases included five of the seven (71%) chromophobe renal cell carcinoma with aggressive features. Statistical analysis showed significant association of CD10-positive tumors with clinicopathologic aggressiveness (P=0.003) and mitotic figures (P=0.04). Parvalbumin was strongly expressed in all primary and metastatic chromophobe renal cell carcinomas. Western blot analysis was utilized to confirm the expression of both CD10 and parvalbumin in chromophobe renal cell carcinomas. 相似文献
78.
Patrizia Nanni Carla De Giovanni Pier-Luigi Lollini Giordano Nicoletti Giorgio Prodi 《Clinical & experimental metastasis》1983,1(4):373-380
A metastasizing mouse cell line (TS/A), originated from a mammary adenocarcinoma which arose spontaneously in a BALB/c female retired breeder, has been established in vitro. It displayed a remarkable morphologic heterogeneity, which is evident in plastic adherent cultures (cell types ranging from epithelial-like to fibroblast-like) as well as in semi-solid agar cultures. The TS/A line exhibited the presence of specific cytoplasmic estradiol receptor, with a binding activity of 16 fmoles/mg cytosol protein. The in vivo growth pattern was as follows: (1) a s.c. inoculum of 105 cells caused a 100 per cent tumor take and kill in syngeneic animals; mean survival time was 54 + 1 days; (2) it did not show significant transplant immunogenicity in syngeneic animals; (3) it was able to give rise to both spontaneous lung metastases and artificial lung colonies; (4) it had a high capacity to grow in H-2 matched, minor histocompatibility antigen incompatible hosts (106 cells killed 100 per cent DBA/2 mice in 58 + 2 days). This line of spontaneous mammary tumor cells is proposed as a useful model for studies on the heterogeneity of the neoplastic population in relation to metastatic spread, on tumor immunogenicity, and on therapy of mammary neoplasia. 相似文献
79.
Fava GA Ruini C Rafanelli C Finos L Salmaso L Mangelli L Sirigatti S 《Psychotherapy and psychosomatics》2005,74(1):26-30
BACKGROUND: There is increasing awareness that the goal of treatment in generalized anxiety disorder (GAD) should not simply be a response, but restoration of normal function. The aim of this study was to apply a novel psychotherapeutic approach for increasing the level of remission in GAD. METHODS: Twenty patients with DSM-IV GAD devoid of comorbid conditions were randomly assigned to 8 sessions of cognitive behavioral therapy (CBT) or the sequential administration of 4 sessions of CBT followed by other 4 sessions of well-being therapy (WBT). Assessment methods included the Anxiety and Depression Scales of Paykel's Clinical Interview for Depression, Ryff's Psychological Well-being Scales and Kellner's Symptom Questionnaire. A one-year follow-up was undertaken. RESULTS: Significant advantages of the CBT-WBT sequential combination over CBT only were observed with both observer and self-rated methods after treatment. Such gains were maintained at follow-up. CONCLUSIONS: These preliminary results suggest the feasibility and clinical advantages of adding WBT to the treatment of GAD. They lend support to a sequential use of treatment components for achieving a more sustained recovery. 相似文献
80.
Francesca Cirulli Daniela Santucci Giovanni Laviola Enrico Alleva Seymour Levine 《Developmental psychobiology》1994,27(5):301-316
These studies investigated behavioral and hormonal responses to stress in developing mice. Experiment 1 examined the effects of 24-hr maternal deprivation on corticosterone (CORT) secretion and ultrasonic vocalization (UVZ) rate in 4-, 8-, and 12-day-old mice. At these ages, exposure to a novel environment resulted in minimal changes in CORT secretion. Maternal deprivation increased pups′ CORT secretion in an age-dependent fashion but did not affect their UVZ rate. The aim of experiment 2 was to test the effects of cholordiazepoxide (CDP), an anxyolytic compound, on CORT secretion and UVZ in both normally reared and in maternally deprived 8-day-old mice. CDP administration elevated CORT increases in deprived (DEP) animals. CDP affected UVZ only in nondcprived (NDEP) animals: UVZ ratewas decreased by high CDP doses Overall, these findings demonstrate that the infant mouse shows a period of stress hyp9oresponsiveness similar to the rat and that maternal presence contributes to inhibit adrenocorticalactivity. CDP administration, butnot novelty exposure, increased CORT secretion in 8-day- old normally reared mice suggesting that during the stress hyporesponsive period, the HPA axis is capable of responding only to specific stimuli. Changes in HPA axis activity and UVZ rateresulting from maternal deprivation and/or CDP challenge do not seem to be directly related. ©1994 John Wiley & Sons, Inc. 相似文献