全文获取类型
收费全文 | 10837篇 |
免费 | 530篇 |
国内免费 | 36篇 |
专业分类
耳鼻咽喉 | 99篇 |
儿科学 | 709篇 |
妇产科学 | 281篇 |
基础医学 | 1175篇 |
口腔科学 | 209篇 |
临床医学 | 623篇 |
内科学 | 2109篇 |
皮肤病学 | 327篇 |
神经病学 | 550篇 |
特种医学 | 277篇 |
外国民族医学 | 1篇 |
外科学 | 1538篇 |
综合类 | 276篇 |
一般理论 | 11篇 |
预防医学 | 442篇 |
眼科学 | 759篇 |
药学 | 1122篇 |
中国医学 | 54篇 |
肿瘤学 | 841篇 |
出版年
2023年 | 78篇 |
2022年 | 194篇 |
2021年 | 378篇 |
2020年 | 189篇 |
2019年 | 257篇 |
2018年 | 286篇 |
2017年 | 224篇 |
2016年 | 280篇 |
2015年 | 280篇 |
2014年 | 374篇 |
2013年 | 529篇 |
2012年 | 754篇 |
2011年 | 801篇 |
2010年 | 439篇 |
2009年 | 321篇 |
2008年 | 578篇 |
2007年 | 559篇 |
2006年 | 475篇 |
2005年 | 448篇 |
2004年 | 424篇 |
2003年 | 356篇 |
2002年 | 343篇 |
2001年 | 290篇 |
2000年 | 294篇 |
1999年 | 245篇 |
1998年 | 95篇 |
1997年 | 65篇 |
1996年 | 84篇 |
1995年 | 64篇 |
1994年 | 46篇 |
1993年 | 43篇 |
1992年 | 117篇 |
1991年 | 159篇 |
1990年 | 126篇 |
1989年 | 106篇 |
1988年 | 107篇 |
1987年 | 75篇 |
1986年 | 85篇 |
1985年 | 89篇 |
1984年 | 65篇 |
1983年 | 68篇 |
1979年 | 66篇 |
1978年 | 44篇 |
1977年 | 35篇 |
1975年 | 34篇 |
1973年 | 38篇 |
1972年 | 41篇 |
1971年 | 44篇 |
1969年 | 32篇 |
1968年 | 44篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Fertility reduction and the quality of family planning services 总被引:5,自引:0,他引:5
A K Jain 《Studies in family planning》1989,20(1):1-16
The purpose of this paper is to determine whether a focus on quality of family planning services is consistent with meeting demographic objectives. An analytical framework that links the six elements of quality with fertility is described. A review of existing literature and analysis suggest that improvements in quality of family planning services by enhancing the choice of contraceptive methods available in a country would increase the overall practice of contraception and thus would result in fertility reduction. 相似文献
42.
Compound 5a ([Z]-1, 1-Dichloro-2,3 diphenyl-2-(4-methoxyphenyl)cyclopropane) is a novel cyclopropyl compound which was shown to be a pure antiestrogen. In the present study, the antiproliferative activity of 5a was examined on estrogen receptor (ER)-positive MCF-7 and ER-negative MDA-MB-231 human breast cancer cells and A-549 human lung cancer cells using the hemocytometric trypan blue exclusion method. Compound 5a inhibited the growth of MCF-7 cells in a dose-related manner over a concentration range of 10(-9) to 10(-5) M, but did not alter the growth of MDA-MB-231 or A-549 cells. Co-administration of estradiol (10(-8) M) reversed the antiproliferative activity of 5a (10(-7) M) on MCF-7 cells. Further, an ER-dependent mechanism of action is supported by the specific ER binding of 5a in MCF-7 cells observed in this study. The influence of 5a on the cell surface morphology of MCF-7 and MDA-MB-231 cells was studied using scanning electron microscopy (SEM). Compound 5a at 10(-6) M reduced the length and density of microvilli (MV) on MCF-7 cells, which was reversed by co-administration of estradiol (10(-8) M). This compound did not alter the cell surface morphology of ER-negative MDA-MB-231 cells. In conclusion, 5a and tamoxifen inhibited the growth of ER-prositive MCF-7 cells in an estradiol-reversible manner, and had no effect on ER-negative MDA-MB-231 cells. The results of this study with human breast cancer cells suggest that 5a may be highly effective in the treatment of estrogen-dependent breast cancer and/or in the prophylactic treatment of women with a high risk of breast cancer development. 相似文献
43.
An unusual case of dorsal spinal dysraphism in a four year old child is presented. Various abnormalities including diastematomyelia, an extradural arachnoid cyst arising from one of the two dural tubes, and lipomeningomyelocele with a related rib-like bony structure were demonstrated with Iohexol CT and subsequently confirmed at surgery. 相似文献
44.
To improve the in vivo performance of engineered implants, this study examines the independent effects of surface chemistry and topography on fibroblast morphology and density in vitro. Titanium (Ti) was sputter-coated onto smooth and microtextured polyethylene terephthalate (PET). Test specimens were evaluated in 24-h, fibroblast cultures and assessed with scanning electron microscopy (SEM) for cellular morphology and density. Fibroblast density increased, as the Ti film thickness increased. The fibroblasts exhibited contact guidance on the textured test specimens. The greatest cellular density was found on the Ti-coated, textured test specimens. In conclusion, Ti and surface texture appeared to strongly influence fibroblast density and morphology as compared to PET and smooth surfaces. 相似文献
45.
Joanne R. Less Mitchel C. Posner Thomas C. Skalak Norman Wolmark Rakesh K. Jain 《Microcirculation (New York, N.Y. : 1994)》1997,4(1):25-33
Objective : To measure the geometric resistance to blood flow in human colorectal carcinoma. Although tumor blood flow is of central importance in both the detection and the treatment of cancer, the determinants of blood flow through the neoplastic circulation are poorly understood. Methods : Human colorectal carcinomas (tissue weight = 272 g ± 43 g (SD), n = 6) were perfused ex vivo with a buffered physiological salt solution of known viscosity at flow rates ranging from 2.5 to 40 ml/min and perfusion pressures from 8 to 100 mm Hg. The geometric resistance was determined from the slope of the pressure-flow curve. For examination of the principal determinant of geometric resistance, the vascular architecture, one of the tumors was perfused with Batson's No. 17 polymer and macerated in KOH to produce a positive vascular cast that was used for measurement of vascular branching patterns and dimensions. Results : The pressure-flow relationship was linear at perfusion pressures above 40 mm Hg, and the geometric resistance, z0, was constant at approximately 6.5 ± 109g/cm3. Below 40 mm Hg, z0 increased rapidly. The architecture of the arteriolar and capillary networks of human colorectal carcinoma is similar to those of experimental rodent tumors. Capillaries in planar and nonplanar mesh-works had mean segment diameters of 11 ± 2 and 9.6 ± 2 μm, lengths of 46 ± 24 and 107 ± 40 μm, and intercapillary distances of 46 ± 13 and 74 ± 24 μm, respectively. Conclusions : The geometric flow resistance in neoplastic tissue is 1–2 orders of magnitude higher than that observed in normal tissues. A decrease in functional vascular cross-sectional area may explain the additional increase in resistance at small perfusion pressures. The observed flow resistance may be due to the specialized arteriolar and capillary network architecture, pressures exerted by proliferating cancer cells, and/or coupling between vascular and extravascular flow. These observations demonstrate that tumor vascularity alone may not be indicative of flow resistance or tumor susceptibility to blood-borne therapeutic agents. 相似文献
46.
47.
48.
Hepatitis induced by traditional Chinese herbs; possible toxic components. 总被引:12,自引:0,他引:12 下载免费PDF全文
Traditional Chinese herbal remedies are widely available in the United Kingdom for the treatment of chronic skin disorders. Their benefits are considerable, but their use is completely unregulated. Two patients are described here who suffered an acute hepatitic illness related to taking traditional Chinese herbs. Both recovered fully. The mixtures that they took included two plant components also contained within the mixture taken by a previously reported patient who suffered fatal hepatic necrosis. These cases high-light the need for greater awareness of both the therapeutic and toxic potential of herbal remedies, as well as greater control of their use. 相似文献
49.
S. S. Borwankar L. S. Kasat A. Naregal M. Jain R. Bajaj 《Pediatric surgery international》1998,14(1-2):129-130
A case of covered exstrophy without sequestration of a bowel segment is reported. A 4-year-old female presented with dribbling
of urine. Treatment to date has been simple excision of the covered membrane with functional closure of the bladder and bilateral
posterior iliac osteotomies, with reconstruction of the bladder neck and genitalia to be performed at a later date. The embryogenesis
of this rare variant, a review of the reported cases, and management options are discussed.
Accepted: 6 November 1997 相似文献
50.
Chen D Ueda R Harding F Patil N Mao Y Kurahara C Platenburg G Huang M 《European journal of immunology》2003,33(1):172-182
Linkage studies indicate close associations of certain HLA alleles with autoimmune diseases. To better understand how specific HLA alleles are related to disease pathogenesis, we have generated an HLA DR3/DQ2 transgenic mouse utilizing a 550-kb yeast artificial chromosome (YAC) construct containing the complete DRalpha, DRbeta1, DRbeta3, DQalpha, and DQbeta regions. The transgenic mouse (4D1/C2D) in an I-Abeta(o) background appears healthy with no signs of autoimmune diseases. Lymphoid tissues as well as CD4(+) T cells develop normally. Characterization of the transgene expression demonstrates that approximately 90% of B cells express high levels of DR3 and 50-70% of B cells express DQ2. CD11c(+) dendritic cells express high levels of DR and DQ. Approximately 12-18% of resting T cells are positive for DR expression, and further up-regulation to 40-50% expression is seen upon activation with anti-CD3/anti-CD28 mAb. These results suggest that the transgenic construct confers a high fidelity to the normal human temporal and spatial expression profile. Analysis of T cell receptor repertoire in transgenic mice confirms that DR3/DQ2 are able to mediate thymic selection. Furthermore, transgenic mice respond to a DR3-restricted antigen, demonstrating antigen processing and presentation by antigen-presenting cells (APC). Purified T cells from ovalbumin (OVA)-immunized 4D1 mice respond to human APC co-cultured with OVA, suggesting appropriate antigen/DR3 or DQ2 recognition by murine T cells. Immunoglobulin isotype switching is also observed, indicating functional T-B cognate interactions. Thus, the DR3/DQ2 transgenic mouse has normal lymphoid development and functionality that are mediated by HLA transgenes and can be used to investigate HLA-associated immunological questions. 相似文献