首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1846篇
  免费   107篇
  国内免费   6篇
耳鼻咽喉   16篇
儿科学   39篇
妇产科学   41篇
基础医学   216篇
口腔科学   46篇
临床医学   261篇
内科学   283篇
皮肤病学   24篇
神经病学   145篇
特种医学   110篇
外科学   296篇
综合类   28篇
一般理论   1篇
预防医学   120篇
眼科学   63篇
药学   163篇
中国医学   17篇
肿瘤学   90篇
  2024年   3篇
  2023年   28篇
  2022年   60篇
  2021年   99篇
  2020年   66篇
  2019年   105篇
  2018年   87篇
  2017年   65篇
  2016年   76篇
  2015年   71篇
  2014年   77篇
  2013年   128篇
  2012年   141篇
  2011年   162篇
  2010年   88篇
  2009年   91篇
  2008年   97篇
  2007年   66篇
  2006年   67篇
  2005年   53篇
  2004年   61篇
  2003年   49篇
  2002年   52篇
  2001年   27篇
  2000年   19篇
  1999年   8篇
  1998年   7篇
  1997年   5篇
  1996年   3篇
  1995年   8篇
  1993年   2篇
  1992年   4篇
  1991年   3篇
  1990年   3篇
  1989年   8篇
  1988年   12篇
  1987年   7篇
  1986年   6篇
  1985年   8篇
  1984年   3篇
  1983年   6篇
  1982年   3篇
  1981年   2篇
  1979年   7篇
  1978年   2篇
  1975年   4篇
  1974年   2篇
  1968年   1篇
  1967年   2篇
  1966年   1篇
排序方式: 共有1959条查询结果,搜索用时 15 毫秒
41.
42.
This study uses the CALPUFF modeling system to examine the impact of a region’s geophysical and meteorological conditions on the dispersion of nitrogen dioxide (NO2) emitted from a new oil refinery proposed by the Newfoundland and Labrador Refining Corporation. The proposed construction site of the refinery in Placentia Bay in Newfoundland is compared to the three Canadian locations of Edmonton, Yarmouth, and Whitehorse due to the differences in their geophysical and meteorological conditions. NO2 was selected as the modeled contaminant for this study due to the many severe ecosystem, health, and societal risks associated with its exposure to humans, animals, and the environment. Differences on the impact of each studied region’s geophysical and meteorological conditions led the proposed construction site in Newfoundland to be the only advisable construction site for this refinery out of the four regions examined. Although Yarmouth is also a coastal region, its geophysical and meteorological conditions cause NO2 to disperse into the land, while in Newfoundland, NO2 is dispersed over water. The maximum NO2 concentrations simulated for Edmonton and Whitehorse are considerably high and exceed the NO2 limit for at least one of the two standards proposed by the Newfoundland and Labrador Department of Environment and Conservation and the National Ambient Air Quality Standard. Results show that a region’s geophysical and meteorological conditions have large impacts on the dispersion of pollutants and require careful consideration when selecting a refinery site.  相似文献   
43.
The outcome of care for patients sentenced to forensic psychiatric care is of importance not only for the patient but also for society, in preventing new crimes. In recent years, a person‐centered perspective is influencing the care, recognizing the design of the physical environment as a therapeutic resource. To capture the complexity of patients’ experience of the physical environment, a qualitative approach is needed. The aim of this study was to investigate the meanings of the patient room as a place and space in forensic psychiatric in‐patient care from the patients’ perspective. An explorative qualitative design was chosen, data were collected by photovoice; a combination of photographs, taken by the patients, followed by interviews. Eleven (N = 11) patients were interviewed. The interviews were analysed by a thematic analysis method. Four themes emerged from the data revealing the meanings of the patient room as a place and space: (i) striving towards normality; (ii) being anchored and protected; (iii) being at‐home and homeness; and (iv) being in communion and meaningfulness. The findings show that the physical environment has a say in patients’ basic needs and a role in maintaining normality. Substandard reveals a lack of respect and dignity towards this patient group. Involving patients in the design process of new facilities can be a way to make progress.  相似文献   
44.
BACKGROUND: Long term results of systemic lysis therapy with ultrahigh-dose urokinase (UHUK) in reopening aorto-iliac occlusive disease have not yet been evaluated. This prospective trial investigates the long-term primary patency rate, the rate of complications and assesses the role of different expected influence parameters on the primary patency rate. PATIENTS AND METHODS: 72 patients with aorto-iliac occlusive disease received daily intravenous infusions of UHUK either until reperfusion or--after at least 3 cycles--no progress in recanalization could be stated on two consecutive days by duplex scanning. RESULTS: Systemic lysis therapy was morphological at least partially successful in 44 patients (61.1%). Concomitant percutaneous transluminal angioplasty was performed in 41 patients (56.9%), surgery in 7 patients (9.7%) and both in further 5 patients (6.9%). In patients without surgery hemodynamical success could be achieved in 39 patients (54.2%) and even more important clinical success in 51 patients (70.8%). Compared to baseline results patients improved significantly in ankle/brachial pressure index and in Fontaine stages (p < 0.001), the same results could be seen after a mean follow-up period of 62 months. Thrombolysis was complicated in 4 patients (5.6%) by macroembolizations but no major bleedings or deaths occurred. Primary patency was 76%, 64%, and 43% after 1, 5 and 10 years. Male sex and distal localization were significantly correlated with lower primary clinical patency. CONCLUSION: Systemic lysis therapy is an alternative to surgical intervention in acute and subacute aorto-iliac occlusive disease, because it offers acceptable long-term results with a low rate of complications.  相似文献   
45.
A series of new Schiff bases bearing 1,2,3‐triazole 12a ? o was designed, synthesized, and evaluated as α‐glucosidase inhibitors. All the synthesized compounds showed promising inhibition against α‐glucosidase and were more potent than the standard drug acarbose. The kinetic study on the most potent compound 12n showed that this compound acted as a competitive α‐glucosidase inhibitor. The docking study revealed that the synthesized compounds interacted with the important residues in the active site of α‐glucosidase.  相似文献   
46.
Double network hydrogels are composed of chemical and physical bonds, whose influences on the macroscopic material properties are convoluted. To decouple these, a model dually crosslinked network with independently tunable permanent and reversible crosslinks is introduced. This is realized by interlinking linear and tetra‐arm poly(ethylenegycol) (PEG) precursors with complementary reactive terminal groups. The former also carries a terpyridine ligand at each end, which forms reversible metallo‐supramolecular bonds upon addition of metal ions. These dual networks display different types and amounts of network defects, as studied by light scattering and proton double‐quantum (DQ) NMR. Dynamic light scattering suggests that the network mesh size decreases upon introduction of metal ions, as supported by a decrease of the residual dipolar coupling constant in NMR. Static light scattering indicates larger static inhomogeneities in those networks composed of stronger ions. This is complemented by a fast solid‐like component in the DQ buildup in NMR, attributed to the formation of nanoscopic clusters of charged complexes. The DQ buildup curves also suggest that the presence of strong physical bonds increases the fraction of mobile segments, like loops and dangling ends. This combined study unveils the interplay of chemical and physical bonds toward the formation of a hierarchical structure.  相似文献   
47.
BackgroundPolycystic Ovarian Syndrome (PCOS) is one of the most common causes of infertility in women.ObjectiveThe current study investigated mental and personality disorders in infertile women with and without PCOS.MethodsThis case-control study evaluated 400 infertile women who referred to the Infertility Center in Babol city (North of Iran). Participants were categorized into the case group (201 PCOS) and the control group (199 without PCOS). All of the participants completed the Millon Clinical Multi-axial Inventory-III (MCMI-III).ResultsThe mean scores for clinical personality patterns were significantly higher for six personality disorders (schizoid, avoidant, antisocial, depressive, sadistic, and negativistic) and for three classes of severe personality disorder patterns (schizotypal, borderline, and paranoid) in infertile women with PCOS than in women without PCOS. The mean scores for eight clinical disorders (somatoform, manic disorder, dysthymia, alcohol-dependence, drug-dependence, post-trauma stress disorder, major depression, and delusion disorder) were also higher in infertile women with PCOS than in women without PCOS.ConclusionThe scores of many mental and personality disorders are higher in infertile women with PCOS than in women without PCOS. Thus, clinicians should prioritize recognizing and treating psychological problems of infertile women with PCOS.  相似文献   
48.
Regulated cell death (RCD) guarantees to preserve organismal homeostasis. Apoptosis and autophagy are two major arms of RCD, while endoplasmic reticulum (ER) as a crucial organelle involved in proteostasis, promotes cells toward autophagy and apoptosis. Alteration in ER stress and autophagy machinery is responsible for a great number of diseases. Therefore, targeting those pathways appears to be beneficial in the treatment of relevant diseases. Meantime, among the traditional herb medicine, kaempferol as a flavonoid seems to be promising to modulate ER stress and autophagy and exhibits protective effects on malfunctioning cells. There are some reports indicating the capability of kaempferol in affecting autophagy and ER stress. In brief, kaempferol modulates autophagy in noncancerous cells to protect cells against malfunction, while it induces cell mortality derived from autophagy through the elevation of p‐AMP‐activated protein kinase, light chain‐3‐II, autophagy‐related geness, and Beclin‐1 in cancer cells. Noteworthy, kaempferol enhances cell survival through C/EBP homologous protein (CHOP) suppression and GRP78 increment in noncancerous cells, while it enhances cell mortality through the induction of unfolding protein response and CHOP increment in cancer cells. In this review, we discuss how kaempferol modulates autophagy and ER stress in noncancer and cancer cells to expand our knowledge of new pharmacological compounds for the treatment of associated diseases.  相似文献   
49.
In today’s society, sleep disturbances and back pain are both common problems which threaten health. Although some studies have focused on the effects of sleep disturbances on back pain, no meta-analysis has been done. The purpose of this study is to systematically review and perform a meta-analysis on the effects of sleep disturbances on back pain. A literature search in PubMed, Scopus and EMBASE with keywords until June 2019 was performed. The eligible articles were evaluated qualitatively and the results were pooled using random effects. The publication bias and the degree of heterogeneity were examined. In all, 21 studies were included in the meta-analysis. Sleep disturbances were associated with back pain (odds ratio 1.52; confidence interval [CI] 1.37–1.68; P < 0.001). In men, the odds ratio was 1.49 (CI 1.34–1.65; P < 0.001). In women, the odds ratio was 1.56 (CI 1.33–1.81; P < 0.001). Begg’s test (P = 0.856) and Egger test (P = 0.188) did not show any publication bias. A funnel plot and trim-and-fill method showed publication bias, and heterogeneity was also high. Sleep disturbance is associated with risk of back pain. Improving sleep can be a deterrent against back pain. Therefore, interventions to reduce sleep disturbances can help to improve health. On the other hand, the relationship between sleep disturbances and back pain can be two-sided, and back pain can also lead to sleep disturbances. Not only in view of the lifetime prevalence and the multifactorial impairments of those affected, but also in consideration of social and economic burdens, this issue will remain of considerable importance.  相似文献   
50.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号