全文获取类型
收费全文 | 5247篇 |
免费 | 310篇 |
国内免费 | 16篇 |
专业分类
耳鼻咽喉 | 86篇 |
儿科学 | 162篇 |
妇产科学 | 228篇 |
基础医学 | 748篇 |
口腔科学 | 309篇 |
临床医学 | 317篇 |
内科学 | 1233篇 |
皮肤病学 | 118篇 |
神经病学 | 481篇 |
特种医学 | 114篇 |
外国民族医学 | 2篇 |
外科学 | 643篇 |
综合类 | 44篇 |
一般理论 | 1篇 |
预防医学 | 321篇 |
眼科学 | 82篇 |
药学 | 422篇 |
中国医学 | 7篇 |
肿瘤学 | 255篇 |
出版年
2023年 | 28篇 |
2022年 | 31篇 |
2021年 | 79篇 |
2020年 | 50篇 |
2019年 | 85篇 |
2018年 | 141篇 |
2017年 | 121篇 |
2016年 | 107篇 |
2015年 | 121篇 |
2014年 | 153篇 |
2013年 | 199篇 |
2012年 | 320篇 |
2011年 | 372篇 |
2010年 | 166篇 |
2009年 | 141篇 |
2008年 | 241篇 |
2007年 | 273篇 |
2006年 | 286篇 |
2005年 | 277篇 |
2004年 | 250篇 |
2003年 | 235篇 |
2002年 | 201篇 |
2001年 | 75篇 |
2000年 | 121篇 |
1999年 | 73篇 |
1998年 | 32篇 |
1997年 | 35篇 |
1992年 | 92篇 |
1991年 | 52篇 |
1990年 | 82篇 |
1989年 | 81篇 |
1988年 | 67篇 |
1987年 | 61篇 |
1986年 | 55篇 |
1985年 | 67篇 |
1984年 | 49篇 |
1983年 | 43篇 |
1982年 | 42篇 |
1981年 | 27篇 |
1980年 | 34篇 |
1979年 | 53篇 |
1978年 | 43篇 |
1977年 | 32篇 |
1976年 | 37篇 |
1975年 | 30篇 |
1974年 | 55篇 |
1973年 | 35篇 |
1972年 | 40篇 |
1971年 | 37篇 |
1969年 | 28篇 |
排序方式: 共有5573条查询结果,搜索用时 15 毫秒
1.
Martin R. Späth Malte P. Bartram Nicolàs Palacio-Escat K. Johanna R. Hoyer Cedric Debes Fatih Demir Christina B. Schroeter Amrei M. Mandel Franziska Grundmann Giuliano Ciarimboli Andreas Beyer Jayachandran N. Kizhakkedathu Susanne Brodesser Heike Göbel Jan U. Becker Thomas Benzing Bernhard Schermer Martin Höhne Markus M. Rinschen 《Kidney international》2019,95(2):333-349
2.
Inflammation but not obesity or insulin resistance is associated with increased plasma fibroblast growth factor 23 concentration in the elderly
下载免费PDF全文
![点击此处可从《Clinical endocrinology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
3.
Micha? Panasiuk Marek Synder Maryla Drynkowska-Panasiuk Oktawiusz Bończak 《Chirurgia narzadów ruchu i ortopedia polska》2006,71(4):265-267
Serum levels of bone markers N-mid osteocalcin (OCN-Mid) and Cross-Laps in 20 patients (8 men and 12 women) with loosening of at least one element of total hip endoprosthesis confirmed during operation were compared with age and sex matched group with OA. Marker levels were measured by direct chemoluminescency using Modular E-170. Statistical analysis were done with t-Student test (alpha = 0.05). There were no significant differences in OCN-Mid, Cross-Laps levels and OCN-Mid/Cross-Laps ratio between both groups. Implant loosening is a slow process taking place on a relatively small surface in comparison to whole skeleton, so bone markers have no clinical value in diagnostics of total hip loosening. 相似文献
4.
Integration and differentiation of human embryonic stem cells transplanted to the chick embryo. 总被引:3,自引:0,他引:3
Ronald S Goldstein Micha Drukker Benjamin E Reubinoff Nissim Benvenisty 《Developmental dynamics》2002,225(1):80-86
Human embryonic stem (ES) cells are pluripotent cells that can differentiate into a large array of cell types and, thus, hold promise for advancing our understanding of human embryology and for contributing to transplantation medicine. In this study, differentiation of human ES cells was examined in vivo by in ovo transplantation to organogenesis-stage embryos. Colonies of human ES cells were grafted into or in place of epithelial-stage somites of chick embryos of 1.5 to 2 days of development. The grafted human ES cells survived in the chick host and were identified by vital staining with carboxyfluorescein diacetate or use of a green fluorescent protein-expressing cells. Histologic analysis showed that human ES cells are easily distinguished from host cells by their larger, more intensely staining nuclei. Some grafted cells differentiated en masse into epithelia, whereas others migrated and mingled with host tissues, including the dorsal root ganglion. Colonies grafted directly adjacent to the host neural tube produced primarily structures with the morphology and molecular characteristics of neural rosettes. These structures contain differentiated neurons as shown by beta-3-tubulin and neurofilament expression in axons and cell bodies. Axons derived from the grafted cells penetrate the host nervous system, and host axons enter the structures derived from the graft. Our results show that human ES cells transplanted in ovo survive, divide, differentiate, and integrate with host tissues and that the host embryonic environment may modulate their differentiation. The chick embryo, therefore, may serve as an accessible and unique experimental system for the study of in vivo development of human ES cells. 相似文献
5.
Micha? Latalski 《Chirurgia narzadów ruchu i ortopedia polska》2007,72(2):129-131
The Internet is becoming a more integral part of daily education for all orthopaedic surgeons. Author presents web sites, which are interesting resources of orthopaedic knowledge. 相似文献
6.
7.
Arik Hasson Michael Fainzilber Eliahu Zlotkin Micha Spira 《The European journal of neuroscience》1995,7(4):815-818
A novel peptide toxin, PnIVB, isolated from the venom of Conus pennaceus blocks voltage-gated sodium current in Aplysia neurons. Complete blockade is obtained at a PnIVB concentration of 80±2.2 nM and 50% blockade at 16±0.86 nM. The potency of PnIVB in blocking Aplysia sodium current is four orders of magnitude larger than that of tetrodotoxin. The toxin has no paralytic activity when injected into fish. The rapid blockade of sodium current by PnIVB is not associated with a change in the activation or inactivation kinetics of the current, or with the reversal potential. Sodium current blockade is reversible after a 30 min wash with 50 times the bath volume. The novel conotoxin PnlVB can be used as a powerful tool for mollusc neurobiological research and as a molecular probe to explore the structure-function relations of voltage-gated sodium channel subtypes. 相似文献
8.
The adaptation rule of Vector Quantization algorithms, and consequently the convergence of the generated sequence, depends on the existence and properties of a function called the energy function, defined on a topological manifold. Our aim is to investigate the conditions of existence of such a function for a class of algorithms including the well-known 'K-means' and 'Self-Organizing Map' algorithms. The results presented here extend several previous studies and show that the energy function is not always a potential but at least the uniform limit of a series of potential functions which we call a pseudo-potential. It also shows that a large number of existing vector quantization algorithms developed by the Artificial Neural Networks community fall into this class. The framework we define opens the way to studying the convergence of all the corresponding adaptation rules at once, and a theorem gives promising insights in that direction. 相似文献
9.
The hepatocarcinogenic responses of rats to aflatoxin B1 (AFB1) are believed to depend on microsomal activation of the toxin, followed by macromolecular binding. Dietary protein insufficiency is reported to reduce the level of microsomal metabolism, and therefore would be expected to reduce the AFB1-induced carcinogenicity. Indeed, diminished hepatocarcinogenicity in low-protein diet fed weanling rats that had received AFB1 has been reported. In the present study, carcinogenicity and other toxic effects of AFB1 (0.5 p.p.m.) fed to weanling male Fischer F344 rats on a low-protein diet (5%) or normal-protein (20%) diet for up to 8 weeks were examined. In our study, in contrast with the previous report, all animals that had survived some initial toxicity were found to have developed hepatic tumors or hyperplastic gamma-glutamyltransferase-positive foci a year later. The low-protein diet also produced sub-acute toxicity after AFB1 exposure in the weanling rats, leading to severe histological changes, and the death of about half the animals after 3-4 weeks of exposure. Animals fed an AFB1-containing normal-protein diet also exhibited AFB1-induced hepatocarcinogenicity, but not the sub-acute toxicity. The levels of hepatic enzymes involved in AFB1 metabolism were examined in animals fed the low- or normal-protein diets in the absence of AFB1. The low-protein diet, fed to 3 week weanlings for the subsequent 5 weeks, decreased hepatic cytochrome P450 levels, as well as the in vitro capacity of microsomal fractions to form AFB1-8,9-dihydrodiol, an index of AFB1-8,9-epoxide formation. Rats on a normal-protein diet did not show these changes. This discrepancy between the observed increase in sub-acute toxicity and decrease in microsomal activities in the low-protein fed animals implies that the toxic effects observed in these rats were not directly related to metabolic activation of the toxin. In contrast to the diminished microsomal in vitro AFB1 activation, however, in vivo AFB1-DNA adduct formation ability in rats receiving the low-protein diet in the absence of AFB1 was found to become elevated more rapidly during the 5 week experimental feeding period, compared with animals receiving the normal-protein diet. This was accompanied by a more rapid fall in the levels of AFB1-glutathione S-transferase isozyme activity in the low-protein fed animals. The results of this study on weanling rats support the importance of AFB1-GSH in protecting against the carcinogenic responses to AFB1, and probably also the sub-acute toxicity of the latter.(ABSTRACT TRUNCATED AT 400 WORDS) 相似文献
10.
Amphetamine-induced mesolimbic dopamine release has been reported to reduce prepulse inhibition of the acoustic startle response. In addition, it is well known that mesolimbic dopamine stimulation leads to hyperactivity. The present study was undertaken to explore the possibility that one or the other measure may be a more sensitive in vivo indicator of dopamine release in the nucleus accumbens by determining if the amphetamine dose-response curves for these two behavioral measures were different. The data indicate that the dose-response curves obtained for the different behavioral measures are identical. These data are consistent with the idea that the same dopamine terminal field supports both prepulse inhibition of the acoustic startle response and dopamine-stimulated hyperactivity. 相似文献