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   3841篇
  免费   240篇
  国内免费   5篇
耳鼻咽喉   17篇
儿科学   109篇
妇产科学   127篇
基础医学   487篇
口腔科学   34篇
临床医学   431篇
内科学   653篇
皮肤病学   85篇
神经病学   386篇
特种医学   72篇
外科学   537篇
综合类   24篇
一般理论   2篇
预防医学   522篇
眼科学   47篇
药学   224篇
中国医学   5篇
肿瘤学   324篇
  2023年   53篇
  2022年   83篇
  2021年   157篇
  2020年   105篇
  2019年   151篇
  2018年   152篇
  2017年   103篇
  2016年   135篇
  2015年   112篇
  2014年   170篇
  2013年   239篇
  2012年   343篇
  2011年   333篇
  2010年   157篇
  2009年   132篇
  2008年   233篇
  2007年   229篇
  2006年   191篇
  2005年   217篇
  2004年   177篇
  2003年   150篇
  2002年   137篇
  2001年   36篇
  2000年   22篇
  1999年   25篇
  1998年   26篇
  1997年   12篇
  1996年   8篇
  1995年   18篇
  1994年   14篇
  1993年   16篇
  1992年   9篇
  1991年   19篇
  1990年   7篇
  1989年   12篇
  1988年   4篇
  1987年   7篇
  1986年   11篇
  1985年   5篇
  1984年   4篇
  1983年   9篇
  1982年   7篇
  1981年   5篇
  1978年   8篇
  1977年   4篇
  1975年   5篇
  1974年   4篇
  1973年   4篇
  1970年   4篇
  1968年   3篇
排序方式: 共有4086条查询结果,搜索用时 15 毫秒
41.
42.
Non-alcoholic fatty liver disease (NAFLD) is largely linked to poor diet, lack of physical activity/exercise, and being overweight. In the absence of approved pharmaceutical agents, lifestyle modification, encompassing dietary change and increased physical activity/exercise to initiate weight loss, is the recommended therapy for NAFLD. Despite this, the use of lifestyle therapy within clinical settings is lacking with limited guidance available about what it should involve, how it should be delivered, and whether it can be feasibly delivered as part of standard care. This paper highlights the evidence for the use of lifestyle modification in NAFLD. While there is evidence to support use of behavioral strategies to support lifestyle behavior change in other clinical populations, these are yet to be assessed in people with NAFLD. However, there is sufficient evidence to suggest that behavioral intervention targeting diet and physical activity to promote weight loss in general is effective and a number of practical strategies are presented on how this could be achieved.  相似文献   
43.
Little is known regarding family planning desires among women living with HIV in the United States. This study aimed to identify factors influencing desire for children in the future among HIV-infected women in Atlanta, Georgia. HIV-infected women ages 18–45 completed an ACASI (audio computer-assisted self-interview) questionnaire. Chi-square, t-tests, and multivariate logistic regression evaluated factors associated with desire for future children. Of 181 participants, 62 (34.3%) expressed desire for children in the future, with increased desire among younger women (age <26) and those with seronegative partners. Concerns for horizontal and vertical HIV transmission were deterrents to future childbearing. Condom use and overall knowledge of transmission risk was low. Over a third of women desiring a child never discussed their desire with a physician. Misinformation regarding HIV transmission risks persists and is a notable concern influencing desire for children. Providers should reassess family planning desires regularly through integrated HIV care.  相似文献   
44.
An immunocytochemical study of dorsal root ganglia, spinal cord and medulla oblongata was performed with antisera against the c-jun proto-oncogene encoded protein. The c-JUN-like immunoreactivity was restricted to the cell nucleus. In the CNS of untreated rats a basal c-JUN-like immunoreactivity was present in the nuclei of two types of neurons: motor and autonomic. Labelled nuclei could be seen in many motoneurons of the ventral horn of the entire length of spinal cord and the lower medulla oblongata, as well as in the area of the nucleus hypoglossus, the dorsal motor nucleus of nucleus vagus, nucleus ambiguus, nucleus facialis, nucleus abducens and motor nucleus of nucleus trigeminus. Additionally, labelled nuclei were found in the preganglionic sympathetic and preganglionic parasympathetic cells of the nucleus intermediolateralis and nucleus intercalatus in the spinal cord. In the medulla oblongata we found a cluster of cells with c-JUN-like immunoreactivity in an area between the dorsomedial part of the oral nucleus spinalis trigeminalis and the lateral border of the knee of facial nerve. Additionally, a second cluster of c-JUN-like immunoreactivity cells was visible between the ventromedial part of the oral nucleus spinalis trigeminalis and the lateral border of the rostral nucleus facialis. Examination of the characteristics of all cell groups with a basal c-JUN-like immunoreactivity in the spinal cord and lower brainstem revealed an overlapping distribution with cholinergic cell groups. Basal c-JUN-like immunoreactivity was also seen in the dorsal root ganglion cells. We examined the factors which can effect the expression of the c-JUN protein. Maximal expression of c-JUN-like immunoreactivity was observed after electrical stimulation of primary afferents. Stimulation of sciatic nerve at a strength sufficient to recruit A delta- and C-fibres produced c-JUN-like immunoreactivity in many nuclei of the ipsilateral dorsal horn of the lumbar spinal cord. c-JUN-like immunoreactivity was first detectable at 30 min following the end of stimulation, reached a maximum after 1 h, remained unchanged for another 1 h and declined to the basal level after 16 h. The distribution of c-JUN-like immunoreactivity in the lumbar cord coincided with the region of termination of sciatic nociceptive afferents. Contralateral c-JUN-like immunoreactivity appeared after 4 h. After noxious mechanical stimulation of the plantar hindpaw c-JUN-like immunoreactivity occurred in the spinal area of termination of nociceptive afferents of the tibial nerve. Noxious stimulation did not provoke additional c-JUN-like immunoreactivity in dorsal root ganglia.(ABSTRACT TRUNCATED AT 400 WORDS)  相似文献   
45.
Althouygh Menkes disease has well‐recognized neurologic, developmental, and cutaneous features, the initial presentation may resemble child abuse. We describe a 5‐month‐old boy with multiple fractures indicative of nonaccidental trauma who was ultimately diagnosed with Menkes disease. Copper deficiency leads to connective tissue abnormalities and may result in subdural hematomas, wormian bones, cervical spine defects, rib fractures, and spurring of the long bone metaphyses. Several of these findings, including fractures and subdural hematomas, may be misinterpreted as child abuse.  相似文献   
46.
Infection of bone tissue, or osteomyelitis, has become a growing concern in modern healthcare due in no small part to a rise in antibiotic resistance among bacteria, notably Staphylococcus aureus. The current standard of care involves aggressive, prolonged antibiotic therapy combined with surgical debridement of infected tissues. While this treatment may be sufficient for resolving a portion of cases, recurrences of the infection and associated risks including toxicity with long‐term antibiotic usage have been reported. Therefore, there exists a need to produce safer, more efficacious options of treatment for osteomyelitis. In order to test treatment regimens, animal models that closely mimic the clinical condition and allow for accurate evaluation of therapeutics are necessary. Establishing a model that replicates features of osteomyelitis in humans continues to be a challenge to scientists, as there are many variables involved, including choosing an appropriate species and method to establish infection. This review addresses the refinement of animal models of osteomyelitis to reflect the clinical disease and test prospective therapeutics. The aim of this review is to explore studies regarding the use of animals for osteomyelitis therapeutics research and encourage further development of such animal models for the translation of results from the animal experiment to human medicine.  相似文献   
47.
48.
Using plasma amyloid beta protein (Abeta42) levels as an intermediate, quantitative phenotype for late onset Alzheimer's disease (LOAD), we previously obtained significant linkage at approximately 80 cM on chromosome 10. Linkage to the same region was obtained independently in a study of affected LOAD sib-pairs. Together, these two studies provide strong evidence for a novel LOAD locus on chromosome 10 that acts to increase Abeta42. VR22 is a large (1.7 Mb) gene located at 80 cM that encodes alpha-T catenin, which is a binding partner of beta catenin. This makes VR22 an attractive candidate gene because beta catenin interacts with presenilin 1, which has many mutations that elevate Abeta42 and cause early onset familial AD. We identified two intronic VR22 SNPs (4360 and 4783) in strong linkage disequilibrium (LD) that showed highly significant association (P=0.0001 and 0.0006) with plasma Abeta42 in 10 extended LOAD families. This association clearly contributed to the linkage at approximately 80 cM because the lod scores decreased when linkage analysis was performed conditional upon the VR22 association. This association replicated in another independent set of 12 LOAD families (P=0.04 for 4783 and P=0.08 for 4360). Bounding of the association region using multiple SNPs showed VR22 to be the only confirmed gene within the region of association. These findings indicate that VR22 has variant(s) which influence Abeta42 and contribute to the previously reported linkage for plasma Abeta42 in LOAD families.  相似文献   
49.
The purpose of this experiment was to determine the interaction between visual and vestibular information during the transition from quiet standing to the completion of a forward step. Six subjects were asked to take one step forward at the sound of an audio tone, with their eyes open or closed, and terminate the step in a standing position. During stimulation trials, galvanic vestibular stimulation (GVS) was delivered 1500 ms before the auditory cue. GVS was delivered at an intensity three-fold that of each subject's quiet stance threshold with either stimulus right, left or no stimulation. Force data were collected from three forceplates for the calculation of centre of pressure (CoP), and kinematic data were used to calculate centre of mass (CoM) and body trajectories. In quiet stance all subjects responded to the GVS perturbation by demonstrating upper body segment roll and whole body sway towards the anode electrode. Unexpectedly, in the presence of vision during quiet stance, the upper body roll response was not attenuated, even though the CoP sway patterns were reduced when vision was available. During the initiation phase of the step, despite ongoing GVS stimulation, there were no significant effects seen in CoM, CoP or upper body roll responses. During step execution, however, both CoM displacement and upper body roll demonstrated significant effects and both responses were significantly reduced when subjects' eyes were open. Analysis of the medio-lateral CoP integrals also indicated a strong stimulation effect between conditions late in the execution phase, which were largely attenuated with vision. The results suggest that the importance of visual and vestibular information varies depending on the phase of the task. In addition, the different integration between visual and vestibular input during quiet standing suggests a dual role for vestibular information. We propose that vestibular information in quiet standing has a role in maintaining whole body postural stability, as well as playing an integral role in the alignment of the body segments in preparation for proper movement execution. Vision was demonstrated to differentially attenuate these responses based on the phase of the task. Thus, visual and vestibular information appear to be integrated differently across the different phases of a forward-stepping task.  相似文献   
50.
Regulation of epidermal proliferation and differentiation is critical for maintenance of cutaneous homeostasis. Interferon Regulatory Factor 6 (Irf6)-deficient mice die perinatally and exhibit ectopic proliferation and defective epidermal differentiation. We sought to determine whether these disruptions of epidermal function were cell autonomous, and used embryonic Irf6(-/-) keratinocytes to understand the specific role of Irf6 in keratinocyte proliferation and differentiation. In the absence of Irf6, keratinocytes exhibited a heterogeneous phenotype with the presence of large cells. Irf6(-/-) keratinocytes displayed increased colony-forming efficiency compared with wild-type cells, suggesting that Irf6 represses long-term proliferation. Irf6 was present at low levels in wild-type keratinocytes in culture, and upregulated after induction of differentiation in vitro, along with upregulation of markers of early differentiation. However, Irf6(-/-) keratinocytes did not express markers of terminal differentiation. Overexpression of Irf6 in wild-type keratinocytes was insufficient to induce expression of markers of differentiation under growing conditions. Together, these results indicated that Irf6 is necessary, but not sufficient, for keratinocyte differentiation. Finally, using a transgenic mouse expressing Lac-Z under the regulation of an enhancer element 9.7 kb upstream of the Irf6 start site, we demonstrated that this element contributes to the regulation of Irf6 in the epidermis and keratinocytes in culture.  相似文献   
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