全文获取类型
收费全文 | 67753篇 |
免费 | 3705篇 |
国内免费 | 171篇 |
专业分类
耳鼻咽喉 | 869篇 |
儿科学 | 1525篇 |
妇产科学 | 1378篇 |
基础医学 | 8976篇 |
口腔科学 | 2611篇 |
临床医学 | 5186篇 |
内科学 | 16920篇 |
皮肤病学 | 1663篇 |
神经病学 | 5946篇 |
特种医学 | 1608篇 |
外科学 | 9158篇 |
综合类 | 325篇 |
一般理论 | 26篇 |
预防医学 | 5797篇 |
眼科学 | 1262篇 |
药学 | 4447篇 |
中国医学 | 250篇 |
肿瘤学 | 3682篇 |
出版年
2024年 | 47篇 |
2023年 | 450篇 |
2022年 | 208篇 |
2021年 | 1114篇 |
2020年 | 658篇 |
2019年 | 1184篇 |
2018年 | 2080篇 |
2017年 | 1246篇 |
2016年 | 1327篇 |
2015年 | 2031篇 |
2014年 | 2076篇 |
2013年 | 3013篇 |
2012年 | 5896篇 |
2011年 | 5753篇 |
2010年 | 2637篇 |
2009年 | 1958篇 |
2008年 | 4892篇 |
2007年 | 5077篇 |
2006年 | 5269篇 |
2005年 | 4958篇 |
2004年 | 4465篇 |
2003年 | 4015篇 |
2002年 | 3889篇 |
2001年 | 1579篇 |
2000年 | 2088篇 |
1999年 | 1007篇 |
1998年 | 232篇 |
1997年 | 170篇 |
1996年 | 178篇 |
1995年 | 152篇 |
1994年 | 128篇 |
1993年 | 117篇 |
1992年 | 140篇 |
1991年 | 127篇 |
1990年 | 80篇 |
1989年 | 91篇 |
1988年 | 76篇 |
1987年 | 69篇 |
1986年 | 85篇 |
1985年 | 83篇 |
1984年 | 105篇 |
1983年 | 64篇 |
1982年 | 83篇 |
1981年 | 74篇 |
1980年 | 81篇 |
1979年 | 51篇 |
1978年 | 42篇 |
1977年 | 40篇 |
1976年 | 35篇 |
1974年 | 37篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Effect of eliminating compensation for pain and suffering on the outcome of insurance claims for whiplash injury 总被引:18,自引:0,他引:18
Cassidy JD Carroll LJ Côté P Lemstra M Berglund A Nygren A 《The New England journal of medicine》2000,342(16):1179-1186
BACKGROUND AND METHODS: The incidence and prognosis of whiplash injury from motor vehicle collisions may be related to eligibility for compensation for pain and suffering. On January 1, 1995, the tort-compensation system for traffic injuries, which included payments for pain and suffering, in Saskatchewan, Canada, was changed to a no-fault system, which did not include such payments. To determine whether this change was associated with a decrease in claims and improved recovery after whiplash injury, we studied a population-based cohort of persons who filed insurance claims for traffic injuries between July 1, 1994, and December 31, 1995. RESULTS: Of 9006 potentially eligible claimants, 7462 (83 percent) met our criteria for whiplash injury. The six-month cumulative incidence of claims was 417 per 100,000 persons in the last six months of the tort system, as compared with 302 and 296 per 100,000, respectively, in the first and second six-month periods of the no-fault system. The incidence of claims was higher for women than for men in each period; the incidence decreased by 43 percent for men and by 15 percent for women between the tort period and the two no-fault periods combined. The median time from the date of injury to the closure of a claim decreased from 433 days (95 percent confidence interval, 409 to 457) to 194 days (95 percent confidence interval, 182 to 206) and 203 days (95 percent confidence interval, 193 to 213), respectively. The intensity of neck pain, the level of physical functioning, and the presence or absence of depressive symptoms were strongly associated with the time to claim closure in both systems. CONCLUSIONS: The elimination of compensation for pain and suffering is associated with a decreased incidence and improved prognosis of whiplash injury. 相似文献
102.
Philippe Normand Pascal Simonet Luc Giasson Patrick Ravel-Chapius J. -André Fortin Maurice Lalonde 《Current genetics》1987,11(4):335-338
Summary A plasmid-like molecule was detected in a strain of the ascomycete Ceratocystis fimbriata Ell. & Halst., a pathogenic fungus of Populus spp. The DNA replicon, designated pFQ501, was found to have a linear structure with a length of 6.0 kb (3.9 × 106 daltons) and a density of 1.685 g/cc. This molecule was found to be associated with the mitochondria and was isolated from the gel; its restriction map was deduced from single and double digestions. 相似文献
103.
Morice P Leblanc E Rey A Baron M Querleu D Blanchot J Duvillard P Lhommé C Castaigne D Classe JM Bonnier P;GCCLCC SFOG 《Human reproduction (Oxford, England)》2005,20(5):1379-1385
BACKGROUND: Results of conservative management of epithelial ovarian cancer (EOC) remain controversial in the literature. The aim of this study was to assess the clinical outcomes and fertility following fertility-sparing surgical management of EOC in a retrospective multicentre study. METHODS: A multicentre retrospective study was performed by members of two French groups. Six inclusion criteria were defined: (i) Histological review by the same pathologist; (ii) age < or =40 years; (iii) conservative management; (iv) complete peritoneal staging; (v) delivery of a platinum-based chemotherapy in stage > or = IC; and (vi) follow-up >1 year. RESULTS: Thirty-four patients fulfilled the inclusion criteria: 30 had stage IA disease; three had stage IC and one had stage IIA. Eleven patients had recurrence: 10 patients had invasive disease and one had borderline recurrence. Among 10 patients with invasive recurrence, initial stage and grade were: stage IA G1, n = 1; stage IA G2, n = 4; stage IA G3, n = 1; and stage> or = IC, n = 4. All patients with stage > IA had recurrence. Ten pregnancies were observed in nine patients. CONCLUSION: Conservative surgery for patients with EOC could be considered in young patients with stage IA G1 disease. This procedure should not be performed in patients with FIGO stage > IA. 相似文献
104.
105.
Ignacio Prieto Charles Tease Nieves Pezzi José M. Buesa Sagrario Ortega Leonor Kremer Alicia Martínez Carlos Martínez-A Maj A. Hultén José L. Barbero 《Chromosome research》2004,12(3):197-213
Cohesins are chromosomal proteins that form complexes involved in the maintenance of sister chromatid cohesion during division of somatic and germ cells. Three meiosis-specific cohesin subunits have been reported in mammals, REC8, STAG3 and SMC1 beta; their expression in mouse spermatocytes has also been described. Here we studied the localization of different meiotic and mitotic cohesin components during prophase I in human and murine female germ cells. In normal and atretic human fetal oocytes, from leptotene to diplotene stages, REC8 and STAG3 colocalize in fibers. In murine oocytes, SMC1beta, SMC3 and STAG3 are localized along fibers that correspond first to the chromosome axis and then to the synaptonemal complex in pachytene. Mitotic cohesin subunit RAD21 is also found in fibers that decorate the SC during prophase I in mouse oocytes, suggesting a role for this cohesin in mammalian sister chromatid cohesion in female meiosis. We observed that, unlike human oocytes, murine synaptonemal complex protein SYCP3 localizes to nucleoli throughout prophase I stages, and centromeres cluster in discrete locations from leptotene to dictyate. At difference from meiosis in male mice, the cohesin axis is progressively lost during the first week after birth in females with a parallel destruction of the axial elements at dictyate arrest, demonstrating sexual dimorphism in sister chromatid cohesion in meiosis. 相似文献
106.
Nilius B Weidema F Prenen J Hoenderop JG Vennekens R Hoefs S Droogmans G Bindels RJ 《Pflügers Archiv : European journal of physiology》2003,445(5):584-588
The family of epithelial Ca(2+) channels (ECaC) is a unique group of highly Ca(2+)-selective channels consisting of two members, ECaC1 and ECaC2. We used carboxyl terminal truncations and mutants to delineate the molecular determinants of the Ca(2+)-dependent inhibition of ECaC. To this end, rabbit ECaC1 was expressed heterologously with green fluorescent protein (GFP) in human embryonic kidney 293 (HEK293) cells using a bicistronic vector. Deletion of the last 30 amino acids of the carboxyl terminus of ECaC1 (G701X) decreased the Ca(2+) sensitivity significantly. Another critical sequence for Ca(2+)-dependent inactivation of ECaC1 was found upstream in the carboxyl terminus. Analysis of truncations at amino acid 635, 639, 646, 649 and 653 disclosed a critical sequence involved in Ca(2+)-dependent inactivation at positions 650-653. C653X showed decreased Ca(2+) sensitivity, comparable to G701X, while E649X lacked Ca(2+)-dependent inactivation. Interestingly, the number of green fluorescent cells, which is an index of the number of transfected cells, was significantly smaller for cells transfected with truncations shorter than E649 than for cells transfected with wild-type ECaC. However, the expression level of GFP was restored in the presence of the ECaC blocker ruthenium red, suggesting that these truncations resulted in deleterious Ca(2+) influx. In conclusion, we have identified two domains in the carboxyl terminus of ECaC1 that control Ca(2+)-dependent inactivation. 相似文献
107.
Multiscale structure of sheet nacre 总被引:20,自引:0,他引:20
Rousseau M Lopez E Stempflé P Brendlé M Franke L Guette A Naslain R Bourrat X 《Biomaterials》2005,26(31):6254-6262
This work was conducted on Pinctada maxima nacre (mother of pearl) in order to understand its multiscale ordering and the role of the organic matrix in its structure. Intermittent-contact atomic force microscopy with phase detection imaging reveals a nanostructure within the tablet. A continuous organic framework divides each tablet into nanograins. Their shape is supposed to be flat with a mean extension of 45nm. TEM performed in the darkfield mode evidences that at least part of the intracrystalline matrix is crystallized and responds like a 'single crystal'. The tablet is a 'hybrid composite'. The organic matrix is continuous. The mineral phase is thus finely divided still behaving as a single crystal. It is proposed that each tablet results from the coherent aggregation of nanograins keeping strictly the same crystallographic orientation thanks to a hetero-epitaxy mechanism. Finally, high-resolution TEM performed on bridges from one tablet to the next, in the overlying row, did not permit to evidence a mineral lattice but crystallized organic bridges. The same organic bridges were evidenced by SEM in the interlaminar sequence. 相似文献
108.
Yoshizawa M Sato T Tanaka A Abe K Takeda H Yambe T Nitta S Nosé Y 《ASAIO journal (American Society for Artificial Internal Organs : 1992)》2002,48(4):443-448
The present study has proposed a new method for estimating the pressure head (P(t)[mm Hg]) and flow (Q(t)[L/min]) of a centrifugal pump on the basis of voltage (V(t)[V]), current (I(t)[A]), and rotational speed (N(t)[k(rpm)]) of the DC motor for a pump without any additional sensors. In the proposed estimation method, two auto-regressive exogenous (ARX) models are employed. One ARX model has an output, P(t) or Q(t), and three inputs, VI(t) = V(t)I(t) and N(t) and the steady state gain (K) of the system from VI(t) to N(t). It can be assumed that K may include the information on viscosity of blood. The coefficient parameters of this ARX model are identified in an off-line fashion before implantation of the pump. After implantation, P(t) or Q(t) is estimated by the same ARX model with the already identified parameters. The other ARX model is used to identify Kon the basis of VI(t) and N(t) in an on-line fashion every time the viscosity of blood may change. In the experiment, a mock circulatory system consisting of a centrifugal pump and a reservoir with 37% glycerin or water was employed. The root mean square error between measured Q(t) and its estimate obtained from the proposed method was 1.66L/min. On the other hand, a different method based on a single ARX model with inputs of VI(t) and N(t), but without the additional input of K, yielded the corresponding estimation error of 2.22L/min. This means that the proposed method can reduce its estimation error by about 25% in comparison with a method that cannot cope with the change in blood viscosity. 相似文献
109.
Rodrigues FC Kawasaki-Oyama RS Fo JF Ukuyama EE Antonio JR Bozola AR Romeiro JG Rahal P Tajara EH 《Cancer Genetics and Cytogenetics》2003,142(2):92-98
The CDKN1A (TP21) gene encodes a 21-kD protein that is a critical downstream mediator of wild-type TP53 and an important regulator of the cell cycle. Failure in the function of this gene would be expected to result in abnormal cell proliferation and transformation. Tumor-associated mutations of the coding region of the TP21 are rare. On the other hand, some TP21 polymorphisms have been identified and characterized by single base substitutions. In the present study, we investigated the potential role of TP21 gene polymorphisms in skin, head, and neck tumorigenesis. A total of 261 samples were examined by polymerase chain reaction single-strand conformational analysis, and one mutation at codon 31 and four polymorphisms in exons 2 (codon 55) and 3 [nucleotide (nt)590] and in promoter region (nt2298) were identified. In conclusion, this investigation confirmed the rarity of mutations in this gene, arguing against a role for TP21 mutations in skin, head, and neck cancers. Also, our results show significant differences in nt2298 allele frequencies between normal individuals and skin malignant tumors (P < 0.05). The results suggest that this polymorphism affects TP21 transactivator binding and may be important during the pathogenesis of skin cancer. 相似文献
110.
Fabrice Bonnet Anne-Christine Jouvencel Marie Parrens Magali Joblon Leon Emmanuelle Cotto Isabelle Garrigue Philippe Morlat Jacques Beylot Hervé Fleury Marie-Edith Lafon 《Journal of clinical virology》2006,36(4):258-263
BACKGROUND: Epstein-Barr virus (EBV) may be causally associated with non-Hodgkin Lymphoma (NHL) in HIV-infected patients. OBJECTIVES: To compare EBV load in whole blood in AIDS-NHL patients, HIV non-AIDS patients and non-HIV-infected persons, and to prospectively measure EBV load in whole blood in AIDS-NHL patients. STUDY DESIGN: Longitudinal and prospective study. RESULTS: We observed no statistical difference in EBV load between AIDS-NHL (3.69log(10) copies/mL [interquartile range (IQR): 2.89-4.27]) and HIV non-AIDS patients (3.08log(10) copies/mL [IQR: 1.29-3.57]) but AIDS-NHL patients had significantly higher EBV loads than HIV-negative controls (1.19log(10) copies/mL [IQR: 0.00-3.29]). We noticed an inverse correlation between CD4+ lymphocytes count and EBV load in patients with AIDS-NHL (r(2)=0.41, P=0.01). In the longitudinal study, the mean EBV load three months after NHL diagnosis decreased significantly (mean difference=-1.69log(10) copies/mL [95% confidence interval: -0.32; -3.04]; P=0.03) under chemotherapy but was still elevated in patients with relapses or no response to chemotherapy. CONCLUSION: Although EBV load seems a suboptimal marker for the diagnosis of AIDS-NHL, we observed a significant decrease of EBV load in patients treated with chemotherapy and a strong association between NHL outcome and EBV load in whole blood. 相似文献