全文获取类型
收费全文 | 5394篇 |
免费 | 379篇 |
国内免费 | 61篇 |
专业分类
耳鼻咽喉 | 51篇 |
儿科学 | 197篇 |
妇产科学 | 142篇 |
基础医学 | 660篇 |
口腔科学 | 132篇 |
临床医学 | 444篇 |
内科学 | 1409篇 |
皮肤病学 | 141篇 |
神经病学 | 459篇 |
特种医学 | 388篇 |
外科学 | 644篇 |
综合类 | 40篇 |
预防医学 | 368篇 |
眼科学 | 61篇 |
药学 | 326篇 |
中国医学 | 6篇 |
肿瘤学 | 366篇 |
出版年
2023年 | 28篇 |
2022年 | 35篇 |
2021年 | 123篇 |
2020年 | 78篇 |
2019年 | 127篇 |
2018年 | 162篇 |
2017年 | 88篇 |
2016年 | 96篇 |
2015年 | 125篇 |
2014年 | 157篇 |
2013年 | 198篇 |
2012年 | 244篇 |
2011年 | 281篇 |
2010年 | 201篇 |
2009年 | 187篇 |
2008年 | 244篇 |
2007年 | 316篇 |
2006年 | 269篇 |
2005年 | 243篇 |
2004年 | 227篇 |
2003年 | 222篇 |
2002年 | 157篇 |
2001年 | 153篇 |
2000年 | 171篇 |
1999年 | 129篇 |
1998年 | 110篇 |
1997年 | 115篇 |
1996年 | 140篇 |
1995年 | 104篇 |
1994年 | 85篇 |
1993年 | 68篇 |
1992年 | 87篇 |
1991年 | 78篇 |
1990年 | 86篇 |
1989年 | 91篇 |
1988年 | 80篇 |
1987年 | 70篇 |
1986年 | 79篇 |
1985年 | 78篇 |
1984年 | 28篇 |
1983年 | 30篇 |
1982年 | 21篇 |
1981年 | 13篇 |
1980年 | 21篇 |
1979年 | 31篇 |
1978年 | 18篇 |
1977年 | 18篇 |
1976年 | 26篇 |
1975年 | 18篇 |
1974年 | 12篇 |
排序方式: 共有5834条查询结果,搜索用时 15 毫秒
41.
42.
Uroscopy in the 21st century: high-field NMR spectroscopy 总被引:1,自引:1,他引:0
Neild GH; Foxall PJ; Lindon JC; Holmes EC; Nicholson JK 《Nephrology, dialysis, transplantation》1997,12(3):404-417
From the experiments described, it can be seen that there are different
research approaches that can be taken and these are summarized in Table 1.
Whereas much scientific research is principally hypothesis led, there
remains, nevertheless, an important place for exploratory research. High
resolution NMR can measure, directly and simultaneously, a wide range of
endogenous metabolites in biological fluids and has the unique capability
of providing structural information on the metabolites detected. It has
proved to be a powerful research tool with which to study inherited
metabolic diseases, renal disease, drug metabolism, and toxicity, and can
be used to monitor the effects of drug therapy. For instance, by using a
library of experimental toxins one can map the metabolic profile of
site-specific nephron injury. With this approach in man one could
eventually take an unknown disease such as Balkan nephropathy and predict
the initial site of tubular injury, the mode of injury and therefore the
kind of toxin capable of producing that injury. NMR spectroscopic
techniques are still advancing rapidly, with ever increasing sensitivity
and sophistication of NMR pulse sequences to enhance structural elucidation
in complex mixtures. Given the advances in directly coupled HPLC-NMR and
even HPLC-NMR-mass spectroscopy it is likely that these technologies in
conjunction with pattern recognition will make major contribution to our
understanding of renal processes and provide new diagnostic insights in the
21st century.
相似文献
43.
44.
Primary histiocytic sarcoma of the spleen associated with erythrophagocytic histiocytosis 总被引:4,自引:0,他引:4
Audouin J Vercelli-Retta J Le Tourneau A Adida C Camilleri-Broët S Molina T Diebold J 《Pathology, research and practice》2003,199(2):107-112
We report an exceptional case of a histiocytic sarcoma presenting as a primary isolated spleen tumor in a 71-year-old woman. The neoplastic cells in the cords and sinuses of the red pulp formed multiple lobulated tumors, which were detected in vivo by ultrasound scan. The medium cells, large cells and the giant cells expressed CD68, a histiocyte-associated marker, lysozyme and S100 protein. All these cells were negative for B- and T-cell markers, cytokeratins, melanosome markers (HMB45) and CD1a (Langerhans' cells). Many tumor cells displayed strong erythrophagocytosis and sometimes lymphocytophagocytosis. In addition, numerous histiocytes with morphology indistinguishable from reactive macrophages also exhibited a strong erythrophagocytosis, and were found in the tumor as well as in the normal splenic parenchyma. Despite multi-agent chemotherapy, the patient suffered from a relapse in the liver, with a rapid fatal outcome. A literature review showed that such a primary splenic presentation with multiple tumors is rare. In contrast, in systemic malignant histiocytosis, secondary spleen involvement occurs more frequently but with diffuse infiltration. The association with a reactive histiocytosis with erythrophagocytosis corresponds to "histiocytic medullary reticulosis", as previously described by Scott and Robb-Smith. 相似文献
45.
Blinded, Externally Controlled Multicenter Evaluation of Light Microscopy and PCR for Detection of Microsporidia in Stool Specimens 总被引:6,自引:4,他引:6
下载免费PDF全文
![点击此处可从《Journal of clinical microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Heinz Rinder Klaus Janitschke Horst Aspck Alexandre J. Da Silva Peter Deplazes Daniel P. Fedorko Caspar Franzen Ursula Futh Frank Hünger Anselm Lehmacher Christian G. Meyer Jean-Michel Molina Jrg Sandfort Rainer Weber Thomas Lscher the Diagnostic Multicenter Study Group on Microsporidia 《Journal of clinical microbiology》1998,36(6):1814-1818
The quality parameters for the detection of microsporidia in identical sets of 50 stool samples were determined for six laboratories where technicians used light microscopy and for six laboratories where technicians used PCR. The average overall sensitivities were 67% (89% for patient samples only) for the PCR laboratories and 54% (80% for patient samples only) for the light microscopy laboratories. Specificities were 98 and 95%, respectively. Differences in results were most apparent between the individual laboratories rather than between the two major methods used. 相似文献
46.
Role of tumor necrosis factor in macrophage leishmanicidal activity in vitro and resistance to cutaneous leishmaniasis in vivo. 总被引:2,自引:6,他引:2
下载免费PDF全文
![点击此处可从《Infection and immunity》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Recombinant human tumor necrosis factor (TNF) and purified murine TNF were both able to activate macrophages to destroy intracellular Leishmania major in vitro. In addition, parasitizing macrophages with L. major markedly increased the ability of the cells to produce TNF. Finally, when mice were vaccinated with an avirulent form of L. major, the animals produced large amounts of TNF but no gamma interferon in response to infection with virulent L. major. Treating these mice with a neutralizing anti-TNF antibody led to partial but not complete inhibition of the resistant state, which suggests that factors other than TNF and gamma interferon contribute to resistance to L. major. 相似文献
47.
Long-term protective immune response elicited by vaccination with an expression genomic library of Toxoplasma gondii 总被引:2,自引:0,他引:2
下载免费PDF全文
![点击此处可从《Infection and immunity》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Fachado A Rodriguez A Molina J Silvério JC Marino AP Pinto LM Angel SO Infante JF Traub-Cseko Y Amendoeira RR Lannes-Vieira J 《Infection and immunity》2003,71(9):5407-5411
Immunization of BALB/c mice with an expression genomic library of Toxoplasma gondii induces a Th1-type immune response, with recognition of several T. gondii proteins (21 to 117 kDa) and long-term protective immunity against a lethal challenge. These results support further investigations to achieve a multicomponent anti-T. gondii DNA vaccine. 相似文献
48.
49.
50.
The effects of co-culture with human fibroblasts on human embryo development in vitro and implantation 总被引:5,自引:0,他引:5
Wetzels AM; Bastiaans BA; Hendriks JC; Goverde HJ; Punt-van der Zalm AP; Verbeet JG; Braat DD 《Human reproduction (Oxford, England)》1998,13(5):1325-1330
In a human in-vitro fertilization (IVF) programme, the effect of co-
culture of embryos with human fibroblasts was evaluated with respect to
pregnancy rate and embryo development. Patients were included in the study
after giving informed written consent. The IVF treatments were randomly
assigned by stratification of both age (<36 versus > or =36 years)
and previous IVF attempts (yes versus no). After fertilization was
established, the zygotes were transferred to a 4-well dish with or without
fibroblasts and cultured for 2 days. On the third day after ovum pick-up
(OPU), cell number and quality [5 (good) to 1 (poor)] of the embryos were
scored and a maximum of three embryos was transferred. Supernumerary
embryos of good quality were cryopreserved. The design of this study was a
group sequential trial with the objective of detecting differences between
pregnancy rates following IVF with conventional incubation or incubation in
co-culture with fibroblasts. This design included one evaluation at
half-way data collection. In the study, 148 patients had an OPU, of whom 77
were allocated to the co-culture group. There was no statistically
significant difference in pregnancy rate, cell number and embryo quality
between the two groups. The ongoing pregnancy rate per embryo transfer was
27% in co-culture and 30% in the conventional culture group. The
implantation rates per transferred embryo were 17 and 18% respectively.
Using a multivariate logistic regression model for the probability of
ongoing pregnancies, the odds ratio of co-culture, adjusted for age and
previous IVF attempts, was not statistically significant. In conclusion,
co-culture with human fibroblasts does not contribute to an improvement of
embryo quality nor to a higher pregnancy rate after IVF in an unselected
group of patients.
相似文献