全文获取类型
收费全文 | 29773篇 |
免费 | 1488篇 |
国内免费 | 695篇 |
专业分类
耳鼻咽喉 | 326篇 |
儿科学 | 625篇 |
妇产科学 | 1118篇 |
基础医学 | 7864篇 |
口腔科学 | 704篇 |
临床医学 | 1823篇 |
内科学 | 2945篇 |
皮肤病学 | 511篇 |
神经病学 | 1731篇 |
特种医学 | 588篇 |
外科学 | 1594篇 |
综合类 | 3008篇 |
预防医学 | 3489篇 |
眼科学 | 310篇 |
药学 | 3230篇 |
3篇 | |
中国医学 | 305篇 |
肿瘤学 | 1782篇 |
出版年
2023年 | 259篇 |
2022年 | 519篇 |
2021年 | 697篇 |
2020年 | 701篇 |
2019年 | 672篇 |
2018年 | 706篇 |
2017年 | 790篇 |
2016年 | 760篇 |
2015年 | 890篇 |
2014年 | 1666篇 |
2013年 | 1712篇 |
2012年 | 1527篇 |
2011年 | 1866篇 |
2010年 | 1438篇 |
2009年 | 1491篇 |
2008年 | 1550篇 |
2007年 | 1433篇 |
2006年 | 1276篇 |
2005年 | 1067篇 |
2004年 | 951篇 |
2003年 | 884篇 |
2002年 | 640篇 |
2001年 | 639篇 |
2000年 | 606篇 |
1999年 | 550篇 |
1998年 | 555篇 |
1997年 | 520篇 |
1996年 | 543篇 |
1995年 | 553篇 |
1994年 | 525篇 |
1993年 | 438篇 |
1992年 | 419篇 |
1991年 | 353篇 |
1990年 | 321篇 |
1989年 | 282篇 |
1988年 | 256篇 |
1987年 | 208篇 |
1986年 | 169篇 |
1985年 | 248篇 |
1984年 | 238篇 |
1983年 | 145篇 |
1982年 | 140篇 |
1981年 | 131篇 |
1980年 | 116篇 |
1979年 | 106篇 |
1978年 | 78篇 |
1977年 | 65篇 |
1976年 | 55篇 |
1974年 | 38篇 |
1973年 | 35篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
本文应用放射免疫测定的方法检测了13例输精管结扎后(平均15.3年,平均年龄50岁)的男性精浆双氢睾酮和睾酮的浓度,另取同年龄组男性13例作为对照。结果表明,精浆睾酮在结扎组(374.54p/ml)和正常对照组(315.64Pg/ml)中没有明显差异,而结扎组精浆中双氢睾酮(46.21pg/ml)却明显低子对照组(184.27pg/ml(p<0.01)。作者认为,输精管结扎对精浆DHT有长期影响,这可能是其对前列腺增生过程产生抑制作用的原因之一。 相似文献
72.
妇科疾病中人乳头瘤病毒感染的分子流行病学调查 总被引:1,自引:0,他引:1
目的:探讨各种妇科疾病与人乳头瘤病毒感染的关系,建立不同妇科疾病和不同年龄段妇女人乳头瘤病毒感染的流行病学资料库。方法:应用反向点杂交技术分别对疾病组1 512例病人标本和正常组500例标本进行HPV检测,所得数据用SPSS 13.0软件包进行统计分析。结果:正常组500例标本中,阳性标本101例,感染率为20.2%,疾病组1 512例标本中,阳性标本523例,感染率为34.6%,其中双重感染82例,占阳性标本的15.7%,多重感染34例,占阳性标本的6.5%,而高危感染340例,感染率为22.5%,占阳性标本的65.0%,其中单纯HPV16亚型感染155例,占所有阳性标本的29.6%;不同年龄段、不同性生活史、不同妇科疾病以及不同首次性生活年龄的HPV感染检出率都有显著性差异。结论:正常组和疾病组的HPV感染率有显著性差异(2χ=36.37,P<0.01)。在HPV感染的普查中可以有重点的选择高危人群,这样更加有针对性,从而大大降低普查成本。 相似文献
73.
从高原部队医院实际出发,阐述了适应新形势谋求新发展应处理好的七个关系:即继承与创新的关系;坚持“姓军为兵的服务方向与对外有偿服务的关系;基础建设与人才建设的关系;日常医疗保障与科研的关系;发挥自身特色与学习借鉴的关系;硬件建设与软件建设的关系;科技研究与成果转化的关系。 相似文献
74.
Human glioma cells obtained from established cell lines (Tp-276MG, Tp-301MG, Tp-378MG, Tp-483MG and U-251MG) were analyzed for the presence of ion channels with the tight-seal voltage clamp technique. The current-voltage relation revealed a marked inward rectification at hyperpolarizing voltages, due to the presence of inward rectifying K-channels in cells from all studied cell lines. These channels were conducting when the membrane potential was more negative than the K-equilibrium potential. The slope conductance for the inward K-currents (gKi) was affected both by [K+]i and [K+]0. gKi was proportional to [K+]0 raised to 0.35 or 0.50, of which the larger value was measured in the presence of low [K+]i (25mM). The rectification was not significantly different in cells perfused with Mg-free EDTA-buffered internal solution. Tl+ was 3.5 times more permaant than K+. gki was blocked by Cs+ (1 mM) in a voltage-dependent way (more effective in the hyperpolarized membrane), and by Na+ (154 mM) depending on voltage and time. From measurements of unitary current events in membrane patches (outside out or cell attached) the conductance of the single inward rectifying channel was estimated to be 27 ± 7 pS. This type of ion channel may be important for K-uptake by glial cells and hence for the K-homeostasis in the brain. 相似文献
75.
Four 50 mg and three 100 mg marketed nitrofurantoin tablets were studied in 14 healthy male subjects. Urine was collected 1, 2, 3, 4, 6, 8, 12, and 23 h after each dose, and nitrofurantoin was assayed by HPLC. The in vitro dissolution of the tablets was determined using USP Apparatus 1 and 2, with 0.1 N hydrochloric acid and pH 7.2 buffer as the dissolution fluids. One of the 50 mg tablets was more rapidly and completely absorbed than the other six products. The incidence of side-effects for this product was as low or lower than the other products. It was determined that the use of the USP Apparatus 1, at 100 rev min-1, with sampling of the pH 7.2 fluid at 30 min, provided for the best overall relationship between the urinary excretion and in vitro dissolution. 相似文献
76.
Eleven palatine tonsils were collected from subjects who underwent tonsillectomy in Christian Medical College Hospital and the route of migration of lymphocytes through the high endothelial vessel was studied under EM. In the interendothelial route, migration of a lymphocyte through HEV wall began with the adhesion of a lymphocyte to the surface of endothelial cells by means of a short cytoplasmic projection in the vicinity of intercellular space. The projection extended into the cleft between adjacent endothelial cells. The lymphocyte migrated through HEV by diapedesis. After the lymphocyte had traversed the interendothelial space, it occupied the subendothelial space. In the transendothelial route, migration of a lymphocyte through HEV was initiated by adherence of the lymphocyte to the endothelial cell. The adherent lymphocyte compressed or invaginated into the cytoplasm of the endothelial cell, entered the endothelial cell, was completely enclosed within the endothelial cell cytoplasm, and emerged from the endothelial cell to occupy the subendothelial space. Evidence is presented from static transmission electron microscopic pictures for the migration of lymphocytes by both interendothelial and transendothelial routes through the high endothelial venule. 相似文献
77.
Mary Ellen Turner Kanwal Kher Tamara Rakusan Lawrence D’Angelo Sudesh Kapur Dena Selby Patricio E. Ray 《Pediatric nephrology (Berlin, Germany)》1997,11(2):161-163
We describe the clinical and pathological findings of the hemolytic uremic syndrome (HUS) in two children with human immunodeficiency
virus (HIV) infection. Both patients presented with microangiopathic hemolytic anemia, thrombocytopenia, and subsequently
developed renal failure. The diagnosis of HUS was confirmed by renal histopathology in both patients. None of these children
presented with bloody diarrhea, evidence of circulating antibody response to Escherichia coli O157 lipopolysaccharide, or other known risk factors for HUS, except for the presence of HIV infection. Each patient was
treated with intravenous plasma infusion and renal replacement therapy. Their clinical course was characterized by non-oliguria
and lack of significant hypertension throughout the acute phase of the disease. Despite these favorable clinical parameters,
both patients developed end-stage renal failure. The etiology of this atypical HUS characterized by poor renal survival remains
unknown and the role of HIV infection in its pathogenesis, although possible, is unclear.
Received March 5, 1996; received in revised form and accepted October 15, 1996 相似文献
78.
79.
Brief interruptions of REM sleep are considered to be part of the REM episode. The maximum allowable duration of such an interruption, which is used to define the end of the REM episode, is currently a matter of debate. Making measurements on individual REM cycles, inter-REM interval analysis was carried out to determine whether the generally adopted 15 minute empirical rule for this maximum needs to be extended to 25 minutes as suggested by several including Kobayashi et al. Our results show that there is no reason to alter the 15 minute rule and that measurements which do not take into account the time-of-night effect may be misleading. The proportion of interrupted REM episodes observed in our population of healthy adults is high. We have therefore also examined in some detail the phenomenology of the temporal evolution of the structure and content of the interrupted REM episodes. Both showed a definite change over the night: the interruptions in the earlier episodes tend to return the system to slow wave sleep while those in the later episodes tend to return it to wake. It is hypothesized that these interruptions reflect a measure of REM sleep pressure and its interaction with both slow wave sleep and wake pressures. 相似文献
80.
Total fluorescence from arterial tissue is influenced by three factors: the absorption coefficient of tissue at a specific
excitation wavelength, the laser excitation power and the fluorescence coefficient which is related to chemical species in
tissue. These various influences were demonstrated by the following experimental results in vitro: (1) the effect of increasing
power on fluorescence intensity, (2) the total fluorescence intensity in normal aorta and plaque and (3) the effect of a chromophore
such as β-carotene on total fluorescence intensity. The fluorescence intensity of normal artery is an incremental function
of laser excitation power, and the fluorescence emission from normal artery compared to fluorescence emission from plaque
is significantly different at the same excitation power. The total fluorescence of normal artery was measured to be twice
as great as that of atheromatous plaque (relative mean ratio of 2.58±0.46 compared to unity,p<0.0002 at 488 nm; relative mean ratio of 2.57±0.51 compared to unity,p<0.0009 at 514 nm). The total fluorescence emission decreases with the increase of β-carotene content in arterial tissue (R=0.97). These emission differences, when intensified by an exogenous chromophore of β-carotene, may provide an improved guidance
signal for diagnosis of plaque from normal artery during laser angioplasty procedures. 相似文献