全文获取类型
收费全文 | 161408篇 |
免费 | 10303篇 |
国内免费 | 1213篇 |
专业分类
耳鼻咽喉 | 2260篇 |
儿科学 | 3019篇 |
妇产科学 | 3741篇 |
基础医学 | 24032篇 |
口腔科学 | 3360篇 |
临床医学 | 15226篇 |
内科学 | 30756篇 |
皮肤病学 | 4342篇 |
神经病学 | 12049篇 |
特种医学 | 8082篇 |
外科学 | 21883篇 |
综合类 | 2160篇 |
现状与发展 | 5篇 |
一般理论 | 81篇 |
预防医学 | 9716篇 |
眼科学 | 4307篇 |
药学 | 13641篇 |
中国医学 | 1597篇 |
肿瘤学 | 12667篇 |
出版年
2023年 | 987篇 |
2022年 | 2740篇 |
2021年 | 4825篇 |
2020年 | 2467篇 |
2019年 | 3585篇 |
2018年 | 4403篇 |
2017年 | 3233篇 |
2016年 | 4189篇 |
2015年 | 5634篇 |
2014年 | 6910篇 |
2013年 | 8368篇 |
2012年 | 12647篇 |
2011年 | 12277篇 |
2010年 | 7246篇 |
2009年 | 6065篇 |
2008年 | 9254篇 |
2007年 | 9122篇 |
2006年 | 8377篇 |
2005年 | 7979篇 |
2004年 | 7119篇 |
2003年 | 6189篇 |
2002年 | 5372篇 |
2001年 | 4377篇 |
2000年 | 4026篇 |
1999年 | 3265篇 |
1998年 | 1309篇 |
1997年 | 989篇 |
1996年 | 949篇 |
1995年 | 862篇 |
1994年 | 750篇 |
1993年 | 642篇 |
1992年 | 1573篇 |
1991年 | 1569篇 |
1990年 | 1353篇 |
1989年 | 1236篇 |
1988年 | 1154篇 |
1987年 | 1030篇 |
1986年 | 1010篇 |
1985年 | 882篇 |
1984年 | 644篇 |
1983年 | 563篇 |
1982年 | 399篇 |
1981年 | 378篇 |
1980年 | 338篇 |
1979年 | 519篇 |
1978年 | 406篇 |
1977年 | 388篇 |
1976年 | 342篇 |
1974年 | 358篇 |
1973年 | 327篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Milton G. Mutchnick MD Horchang H. Lee MD 《Alcoholism, clinical and experimental research》1988,12(1):155-158
Concanavalin A-induced lymphocyte proliferation was studied in 25 patients with alcoholic hepatitis or compensated alcoholic cirrhosis. Nine alcoholics without evidence of liver disease were also evaluated. A nonlinear correlation equation, which was natural logarithmic, was applied to individual dose-response proliferation curves and permitted comparisons between patient groups and controls. The proliferative response in all patient groups was significantly lower when compared to healthy controls and was independent of the presence or absence of liver disease. This suggests that some changes in immune function observed in alcoholics may be linked to the direct effects of alcohol on the immune system rather than to the associated liver disease. 相似文献
12.
Summary— KR31080 (2-butyl-5-methyl-6-(1-oxopyridin-2-yl)-3-[[2'-(1H-tetrazol-5-yl) biphenyl-4-yl]methyl]-3H-imidazo[4,5-b] pyridine) is a potent inhibitor of angiotensin type 1 (AT1 ) receptors in rabbit aorta and human recombinant AT1 receptors. In the isolated rabbit thoracic aorta, KR31080 caused a nonparallel shift to the right of the concentration-response curves to angiotensin II (All) with decreased maximal response (pD'2 = 10.1 ± 0.1), but had no effect on the contractile response induced by norepinephrine. KR31080 inhibited specific [125 I]AII binding to rabbit aortic membranes (AT, receptors) and [125 I][Sar1 , Ile8 ]AII binding to human recombinant AT1 receptors in a concentration-dependent manner with IC50 values of 0.84 ± 0.08 nM and 1.92 ± 0.15 nM, respectively, but did not inhibit specific [125 I)AII binding to bovine cerebellum membranes (ÀT2 receptors). In the Scatchard analysis, KR31080 interacted with rabbit aortic AT1 receptors in a competitive manner, similar to losartan. These results demonstrate that KR31080 is a potent and AT1 selective angiotensin receptor antagonist which exerts a competitive antagonism in the [125 I]AII binding assay and insurmountable AT1 receptor antagonism in the functional study. 相似文献
13.
OBJECTIVE: To determine the most frequent clinical causes of a prolonged activated partial thromboplastin time (APTT) result, and to determine whether a new heparin-removal device (the Hepchek, Pall Biomedical, Glen Cove, NY 11542) is capable of efficiently detecting the causes of these values. DESIGN: A combination of chart review and laboratory testing comparing the criterion standard--the heparin chromogenic substrate assay--with the Hepchek. Laboratory investigations were blinded and controlled. SETTING: Inpatient, acute-care hospital. PATIENTS: A total of 1,000 hospital patients with a variety of hemostatic disorders. MAIN OUTCOME MEASURE: The extent to which the Hepchek accurately identified the etiology of a prolonged APTT result. RESULTS: The APTT was prolonged in 25.2% of samples. The presence of heparin in the sample was confirmed by chromogenic assay or by using the Hepchek heparin-removal filter. The presence of heparin was confirmed in 12.8% of all samples and in more than 50% of all abnormal samples. The cause of the abnormal APTT was often unappreciated by the clinician. Bayesian analysis of the Hepchek's ability to diagnose heparin correctly as the cause of the abnormal APTT showed a sensitivity of 100% and specificity of 99.9%. CONCLUSION: Use of the Hepchek in the routine clinical laboratory is an efficient and rapid method of detecting heparin as a cause of isolated prolonged APTT results, and should reduce demands for unwarranted coagulation analyses and inappropriate treatment with blood products. 相似文献
14.
15.
Previously, we prepared two different monoclonal antibodies (mAbs) against human 4-1BB (CD137): an agonistic mAb BBK-1 and an antagonistic mAb BBK-2. In this paper, we describe the molecular cloning of these two mAbs and present comparisons of their amino acid sequences. cDNAs encoding the heavy (H) and light (L) chains of the two mAbs were cloned by screening of cDNA libraries constructed from hybridomas secreting these mAbs. Comparisons of amino acid sequences of the two mAbs showed that, while the constant regions of the H and L chains were identical between the two mAbs, the variable region showed 45% identity in H chains and 48% identity in L chains. This suggests that these two mAbs recognize different epitopes of 4-1BB and may have different effects on the activity of 4-1BB. 相似文献
16.
B Lu J M Lee R Elliott C F Dreyfus J E Adler I B Black 《Brain research. Molecular brain research》1991,11(3-4):359-362
Nerve growth factor (NGF) gene expression in central nervous system (CNS) glia appears to be associated with active glial growth. To study the underlying molecular mechanisms, we examined the effects of a number of growth-related factors on NGF mRNA expression in glial cultures. Our results suggest that glial membrane interaction, as a consequence of growth, actively inhibits NGF gene expression in CNS glia. 相似文献
17.
Controlled release of lidocaine hydrochloride from the surfactant-doped hybrid xerogels. 总被引:2,自引:0,他引:2
We investigate the controlled release of lidocaine hydrochloride from the doped silica-based xerogels. In the xerogel preparation, tetraethoxysilane (TEOS), methyltriethoxysilane (MTES), and propyltriethoxysilane (PTES) are used as precursors, and a nonionic surfactant Igepal CO 720 is used as a dopant. The experimental results suggest that the release of lidocaine hydrochloride can be easily controlled by partially substituting TEOS with the organosilanes, and/or by adding the dopant. Adding the organosilane precursors lowers the release of both the drug and the surfactant in the order of TEOS, MTES/TEOS, and PTES/TEOS xerogels. The release from the PTES/TEOS xerogels is much lower than that from the other xerogels. The release of lidocaine hydrochloride is obviously suppressed by the addition of Igepal CO 720, while the release of Igepal CO 720 is slightly promoted by the addition of the drug. The overall release process is found to be diffusion-controlled, and the release behaviors can be well explained by considering the effects of the textual properties of the xerogels and the interactions among the drug, the surfactant, and the xerogel matrices. 相似文献
18.
K J Meador J L Thompson D W Loring A M Murro D W King B B Gallagher G P Lee J R Smith H F Flanigin 《Neurology》1991,41(6):869-872
Although there has been extensive examination of the behavioral and physiologic correlates of hippocampal theta activity in animals, the human literature consists of a single case study. We investigated the differential effects of four behavioral states on human hippocampal theta activity in 16 epilepsy surgery patients. Behavioral conditions included resting eyes closed (RC), resting eyes open (RO), eyes open with auditory word activation (AW), and eyes open with visuospatial activation (VS). Hippocampal theta activity decreased during both RO and VS compared to both RC and AW. There were reciprocal changes in delta activity. Comparisons of RO to VS and of RC to AW were nonsignificant. The results demonstrate state-specific changes in human hippocampal theta and are consistent with the animal literature that relates hippocampal theta to sensorimotor integration and forebrain volitional mechanisms. 相似文献
19.
20.
Diane Lee Proctor 《Children's Health Care》1987,16(1):13-17
The purpose of this study was to examine the levels of anxiety of mothers with children in pediatric intensive care units with different types of visitation policies, both structured and individualized Forty subjects were obtained from two children's hospitals A comparative research design was used Data showed that mothers who experienced individualized visitation had significantly lower anxiety scores (p < 005) than mothers who experienced structured visitation Findings also revealed that mothers viewed their child's illness as less severe when individualized visitation was permitted as opposed to structured visitation. 相似文献