全文获取类型
收费全文 | 1451篇 |
免费 | 67篇 |
国内免费 | 151篇 |
专业分类
耳鼻咽喉 | 3篇 |
儿科学 | 59篇 |
妇产科学 | 11篇 |
基础医学 | 134篇 |
口腔科学 | 28篇 |
临床医学 | 190篇 |
内科学 | 329篇 |
皮肤病学 | 48篇 |
神经病学 | 39篇 |
特种医学 | 341篇 |
外科学 | 70篇 |
综合类 | 24篇 |
预防医学 | 45篇 |
眼科学 | 20篇 |
药学 | 162篇 |
1篇 | |
中国医学 | 5篇 |
肿瘤学 | 160篇 |
出版年
2024年 | 1篇 |
2023年 | 7篇 |
2022年 | 2篇 |
2021年 | 21篇 |
2020年 | 17篇 |
2019年 | 15篇 |
2018年 | 24篇 |
2017年 | 23篇 |
2016年 | 21篇 |
2015年 | 29篇 |
2014年 | 52篇 |
2013年 | 52篇 |
2012年 | 63篇 |
2011年 | 55篇 |
2010年 | 52篇 |
2009年 | 52篇 |
2008年 | 50篇 |
2007年 | 137篇 |
2006年 | 53篇 |
2005年 | 50篇 |
2004年 | 21篇 |
2003年 | 12篇 |
2002年 | 28篇 |
2001年 | 35篇 |
2000年 | 15篇 |
1999年 | 26篇 |
1998年 | 78篇 |
1997年 | 77篇 |
1996年 | 71篇 |
1995年 | 63篇 |
1994年 | 43篇 |
1993年 | 52篇 |
1992年 | 9篇 |
1991年 | 17篇 |
1990年 | 12篇 |
1989年 | 55篇 |
1988年 | 31篇 |
1987年 | 33篇 |
1986年 | 27篇 |
1985年 | 23篇 |
1984年 | 21篇 |
1983年 | 14篇 |
1982年 | 29篇 |
1981年 | 15篇 |
1980年 | 18篇 |
1979年 | 7篇 |
1978年 | 4篇 |
1977年 | 16篇 |
1976年 | 28篇 |
1975年 | 13篇 |
排序方式: 共有1669条查询结果,搜索用时 46 毫秒
101.
Kobayashi H Shin-Ya K Nagai K Suzuki K Hayakawa Y Seto H Yun BS Ryoo IJ Kim JS Kim CJ Yoo ID 《The Journal of antibiotics》2001,54(12):1013-1018
Glutamate, an excitatory amino acid, is known to induce neurotoxicity in central nervous system under abnormal conditions such as ischemia, hypoglycemia, epilepsy, Huntington's chorea, Parkinson's disease and Alzheimer's disease. In our search for neuroprotective agents of microbial origin against excitatory neurotoxins, we have isolated two new bicyclohexapeptides, neuroprotectins A and B, together with a known compound complestatin, from the fermentation broth of Streptomyces sp. Q27107. Neuroprotectins protected primary cultured chick telencephalic neurons from glutamate- and kainate-induced excitotoxicities in a dose-dependant fashion. 相似文献
102.
103.
Antiparkinsonian drugs are thought to act largely through the D2 receptor family that includes the D(2) and D(3) receptors. D(2) and D(3) receptors exhibit both complementary and overlapping expression at the macro and cellular level. The D(3) receptor appears to be a primary target of the mesolimbic dopamine system, is highly enriched in expression within the "limbic" striato-pallidal-thalamic loop, and is recognized as being regulated by dopaminergic activity in distinctly different ways from the D(2) receptor. In Parkinson's Disease it has been determined that loss of dopaminergic innervation results in elevation of the D(2) receptor but reduced levels of the D(3) receptor. In many late-stage Parkinson's Disease patients there is a loss of antiparkinsonian response to L-dopa and other antiparkinsonian drugs that is often correlated with clinical signs for dementia. We have determined that the reduction of D(3) receptor, and not that of the D(2) receptor, is associated with the loss of response to L-dopa and other antiparkinsonian drugs. The reduction of D(3) receptor is also related to the presence of dementia. An elevation of D(3) receptors was evident in those Parkinson's Disease cases with continued good response to L-dopa. Thus, we believe that reduced D(3) receptor number is correlated with certain subgroups of Parkinson's Disease and may also be related to a further diminishment in the mesolimbic DA system. 相似文献
104.
We performed two-phase helical CT in 31 patients with juxtasellar region and cerebellopontine angle tumours to evaluate its
usefulness in differentiating meningiomas from neurogenic tumours. After the intravenous injection of 90 ml contrast medium
at 3 ml/s, axial helical images were obtained with delays of 30 and 120 s. After the delayed axial images, we acquired coronal
images. Changes in attenuation were assessed visually and quantitatively (by comparing the attenuation in Hounsfield units).
There were 17 meningiomas and 14 neurogenic tumours, all pathologically proven. Two-phase helical CT showed a decrease in
attenuation in 15 (88 %) meningiomas and an increase in 14 (100 %) neurogenic tumours from early to delayed axial images.
Coronal images showed a decrease in attenuation in all 17 meningiomas and an increase in 13 (93 %) of the neurogenic tumours.
The mean HU and their ratios were significantly different between meningiomas and neurogenic tumours.
Received: 22 August 2000 Accepted: 13 October 2000 相似文献
105.
It has been generally accepted that high density lipoprotein cholesterol (HDL-C) level decreases with menopause in women. However, recent reports show different results. There is very little data concerning perimenopausal women. To verify these findings, lipids and lipoprotein(a) [Lp(a)] levels were compared among pre-, peri- and postmenopausal women of similar mean ages. Postmenopausal women had higher HDL-C levels than premenopausal women (p<0.001) and there was no difference between peri- and postmenopausal women. LDL-C level in perimenopausal women was lower than in postmenopausal women (p<0.001) and higher than in premenopausal women with borderline significance (p=.051). Total cholesterol levels showed stepwise elevation from premenopause to postmenopause. Perimenopausal women had lower Lp(a) levels than postmenopausal women (p<0.0005) and similar levels to premenopausal women. Lp(a) levels between 0.1 to 10.0 mg/dL were the most prevalent in pre- and perimenopausal women, and those between 10.1 to 20.0 mg/dL in postmenopausal women. In conclusion, menopause itself is associated with the elevation of HDL-C level, and the postmenopausal increase of coronary artery disease is not related to postmenopausal change of HDL-C level. Perimenopausal status, although transient, may favor Lp(a) and lipid profiles for delaying atherosclerosis. 相似文献
106.
Excel97在药物分析中的应用 总被引:1,自引:0,他引:1
目的:在药物分析中,电子表格软件MicrosoftExce197for Windows。方法:利用Excel的数据处理功能,进行药物的图表绘制、数据计算和统计处理,回归分析,特别是计算分析,并可建立分析数据库。结果和结论:Excel操作简单,功能强大,数据分析工作直观。 相似文献
107.
目的:比较国产辛伐他汀与进口辛伐他汀治疗原发性高胆固醇血症的疗效及安全性。方法:采用开放区组随机对照、多中心的临床设计。150例高胆 固醇血症病人分为验证组(50例)、对照组(48例)和开放组(52例),剂量均为每晚顿服10mg,服药8周。结果:验证组与对照组服药前后比较,血清总胆 固醇(TC)分别降低26.36%和28.3%,低密度脂蛋白胆固醇(LDL-C)分别降低33.17%和35.51%;验 相似文献
108.
Diet and cancer prevention: the fiber first diet 总被引:3,自引:0,他引:3
Diet can play a major role in cancer prevention. The international
differences in cancer incidence are largely accounted for by lifestyle
practices that include nutrition, exercise, and alcohol and tobacco use.
About 50% of cancer incidence and 35% of cancer mortality in the U.S.,
represented by cancers of the breast, prostate, pancreas, ovary,
endometrium, and colon, are associated with Western dietary habits. Cancer
of the stomach, currently a major disease in the Far East, relates to
distinct, specific nutritional elements such as excessive salt intake. For
these cancers, information is available on possible initiating genotoxic
factors, promoting elements, and prophylactic agents. In general, the
typical diet in the United States contains low levels of the potent
carcinogenic agents, heterocyclic amines, formed during the cooking of
meats. It provides only about half the potent appropriate fiber intake and
is high in calories. About twice as many calories as would be desirable
come from fat, certain kinds of which enhance the development of cancers.
Other foods with functional properties, such as soy products and tea, can
be beneficial. To achieve reduction in risk of certain cancers, diet must
be optimized, primarily to reduce caloric intake and the fat component. The
latter should be 20% or less of total caloric intake and fiber should be
increased to 25- 35 g per day for adults. One approach to achieving these
goals is the Fiber First Diet, a diet designed around adequate fiber intake
from grains, especially cereals, vegetables, legumes, and fruits, which
thereby reduces both calorie and fat intake. Such dietary improvements will
not only reduce cancer and other chronic disease risks, but will contribute
to a healthy life to an advanced age. A corollary benefit is a lower cost
of medical care.
相似文献
109.
In the Orient there is a high frequency of residual intrahepatic stones after biliary tract surgery. Percutaneous removal of residual intrahepatic stones was attempted in a group of 74 patients. Stones were exclusively intrahepatic in 57 patients, whereas 17 patients also had stones in the common bile duct. Biliary strictures were present in 60 cases (81%). A combination of techniques was used, including preshaped angulated catheters, irrigation-suction, balloon dilation of strictures, and crushing of large stones. In 36 cases all stones were removed and in 14 cases most stones were removed, for a success rate of 67.6%. Biliary stricture was the factor most often responsible for failure. 相似文献
110.
Activation and complexation of protein C and cleavage and decrease of protein S in plasma of patients with intravascular coagulation 总被引:2,自引:0,他引:2
Activated protein C (APC) is inhibited by two major plasma inhibitors (PCIs). To find evidence for in vivo complexation of APC, immunoblotting studies were performed on plasmas of 85 patients with suspected disseminated intravascular coagulation (DIC). Samples from 62 of these patients contained 5% to 35% of protein C antigen in APC:inhibitor complexes, indicating that protein C activation and inhibition had occurred. In 24 normal plasmas, no detectable APC:PCI complexes were observed (less than 5%). Patients with higher levels of complexes had more abnormal coagulation test data for DIC. The major band of APC complexes detected by anti-protein C antibodies did not react with antibodies to the heparin-dependent protein C inhibitor (PCI- 1) previously described. Rather, APC was complexed with another recently described plasma protein C inhibitor, PCI-2. Immunoblotting studies for protein S, the cofactor for APC, revealed that the majority of the DIC patient plasmas contained a higher than normal proportion of protein S in cleaved form, suggesting that protein S may have been proteolytically inactivated. Protein S total antigen levels were also found to be low in DIC patients, excluding those with malignancy. These studies support the hypothesis that the protein C pathway is activated during DIC. 相似文献