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   5599篇
  免费   262篇
  国内免费   53篇
耳鼻咽喉   56篇
儿科学   86篇
妇产科学   78篇
基础医学   617篇
口腔科学   67篇
临床医学   374篇
内科学   1611篇
皮肤病学   44篇
神经病学   413篇
特种医学   204篇
外科学   1072篇
综合类   17篇
一般理论   2篇
预防医学   122篇
眼科学   66篇
药学   513篇
中国医学   12篇
肿瘤学   560篇
  2023年   28篇
  2022年   56篇
  2021年   81篇
  2020年   50篇
  2019年   78篇
  2018年   84篇
  2017年   60篇
  2016年   105篇
  2015年   100篇
  2014年   149篇
  2013年   145篇
  2012年   230篇
  2011年   271篇
  2010年   149篇
  2009年   143篇
  2008年   269篇
  2007年   263篇
  2006年   252篇
  2005年   248篇
  2004年   229篇
  2003年   244篇
  2002年   237篇
  2001年   219篇
  2000年   223篇
  1999年   211篇
  1998年   58篇
  1997年   38篇
  1996年   36篇
  1995年   33篇
  1994年   41篇
  1993年   21篇
  1992年   143篇
  1991年   147篇
  1990年   155篇
  1989年   176篇
  1988年   126篇
  1987年   134篇
  1986年   110篇
  1985年   112篇
  1984年   68篇
  1983年   47篇
  1982年   22篇
  1979年   38篇
  1978年   27篇
  1977年   19篇
  1975年   18篇
  1974年   24篇
  1972年   28篇
  1971年   23篇
  1969年   20篇
排序方式: 共有5914条查询结果,搜索用时 93 毫秒
181.
Demyelinating Charcot–Marie–Tooth disease (CMT) and chronic inflammatory demyelinating polyneuropathy (CIDP) are both demyelinating polyneuropathies. The differences in nerve enlargement degree and pattern at multiple evaluation sites/levels are not well known. We investigated the differences in nerve enlargement degree and the distribution pattern of nerve enlargement in patients with demyelinating CMT and CIDP, and verified the appropriate combination of sites/levels to differentiate between these diseases. Ten patients (aged 23–84 years, three females) with demyelinating CMT and 16 patients (aged 30–85 years, five females) with CIDP were evaluated in this study. The nerve sizes were measured at 24 predetermined sites/levels from the median and ulnar nerves and the cervical nerve roots (CNR) using ultrasonography. The evaluation sites/levels were classified into three regions: distal, intermediate and cervical. The number of sites/levels that exhibited nerve enlargement (enlargement site number, ESN) in each region was determined from the 24 sites/levels and from the selected eight screening sites/levels, respectively. The cross-sectional areas of the peripheral nerves were markedly larger at all evaluation sites in patients with demyelinating CMT than in patients with CIDP (p < 0.01). However, the nerve sizes of CNR were not significantly different between patients with either disease. When we evaluated ESN of four selected sites for screening from the intermediate region, the sensitivity and specificity to distinguish between demyelinating CMT and CIDP were 0.90 and 0.94, respectively, with the cut-off value set at four. Nerve ultrasonography is useful to detect nerve enlargement and can clarify morphological differences in nerves between patients with demyelinating CMT and CIDP.  相似文献   
182.
183.
184.

Purpose

Primary spinal osteosarcoma is quite rare, and the 5-year survival rate is very low. Because of its rarity, successful treatment experience with spinal osteosarcoma is limited. The purpose of this study is to report the effect of therapy of primary osteosarcoma of spine by carbon-ion radiotherapy (CIRT) and long-term follow.

Methods

A 70-year-old with primary spinal osteosarcoma who received CIRT underwent combined anterior artificial vertebral body replacement and posterior lumbar fusion (L1–L5) 3 years later.

Results

According to the surgical resection of tumoral lesion, pathological results showed that the intertrabecular space previously filled with tumor cells on the initial biopsy sample now contained necrotic tissue without tumor cells. This means that primary osteosarcoma of the spine was completely eliminated and achieved local control with CIRT, with a 7-year follow-up after the initial treatment.

Conclusions

Carbon ion beam treatment is an effective local treatment for patients with spinal osteosarcoma for whom surgical resection is not a feasible option, especially for elderly patients. However, more patients need to be evaluated over a longer term to assess the curative effect of CIRT.
  相似文献   
185.

Purpose

The purpose of this study was to determine which morphokinetic variables are related to embryo gender in a cohort of consecutive live births obtained through single blastocyst transfer following mild ovarian stimulation.

Methods

Eighty-one live births (49 % of them females) from successfully treated, consecutive infertile patients (maternal age 36.9?±?3.8 years, range 28–46) who underwent minimal ovarian stimulation, prolonged embryo culture in a time-lapse monitoring (TLM) incubator and elective single blastocyst transfers during 2012–2014. Early (PNf, t2–t9, cc2a, b, s2, s3) and late (tM, tSB, tfullB, texpB1, and texpB2) morphokinetic variables were scored according to published consensus criteria and were normalized to the time of pronuclear fading. For each variable, the ranges with the highest proportion of female embryos (optimal range) were determined by detailed examination of histograms.

Results

Female embryo gender was associated both with late cleavage (t8), morula (tM), and blastocyst stage morphokinetic variables. The strongest associations (adjusted ORs, 7.0–7.8) were found for late, expanded stage blastocyst parameters; tfullB, texpB1, and texpB2. The proportion of female embryos was 69–71 and 25–26 % inside and outside of the optimal ranges, respectively. This allowed to predict 74–78 % of them, increasing their proportion by 57 % compared to the average.

Conclusions

Although the sample size of our cohort was limited, our findings suggest that several expanded blastocyst stage morphokinetic parameters are associated with female embryo gender. If confirmed on a larger sample these could be potentially used to increase the proportion of female embryos among non-invasively selected blastocysts following single embryo transfer.
  相似文献   
186.
The characterization of the cross-reactive antigens of two closely related apicomplexan parasites, Neospora caninum and Toxoplasma gondii, is important to elucidate the common mechanisms of parasite-host interactions. In this context, a gene encoding N. caninum ribosomal phosphoprotein P0 (NcP0) was identified by immunoscreening of a N. caninum tachyzoite cDNA expression library with antisera from mice immunized with T. gondii tachyzoites. The NcP0 was encoded by a gene with open reading frame of 936 bp, which encoded a protein of 311 amino acids. The NcP0 gene existed as a single copy in the genome and was interrupted by a 432 bp intron. The NcP0 showed 94.5% amino acid identity to T. gondii P0 (TgP0). Anti-recombinant NcP0 (rNcP0) sera recognized a native parasite protein with a molecular mass of 34 kDa in Western blot analysis. Immunofluorescence analysis showed that the NcP0 was localized to the surface of N. caninum tachyzoites. A purified anti-rNcP0 IgG antibody inhibited the growth of N. caninum and T. gondii in vitro in a concentration-dependent manner. These results indicate that P0 is a cross-reactive antigen between N. caninum and T. gondii and a potential common vaccine candidate to control both parasites.  相似文献   
187.
We performed fixation using laminar screws in 2 patients in whom lateral mass screws, pedicle screws or transarticular screws could not be inserted. One was a 56-year-old woman who had anterior atlantoaxial subluxation (AAS). When a guide wire was inserted using an imaging guide, the hole bled massively. We thought the re-insertion of a guide wire or screw would thus increase the risk of vascular injury, so we used laminar screws. The other case was an 18-year-old man who had a hangman fracture. Preoperative magnetic resonance angiography showed occlusion of the left vertebral artery. A laminar screw was inserted into the patent side (i.e., the right side of C2). Cervical pedicle screws are the most biomechanically stable screws. However, their use carries a high risk of neurovascular complications during screw insertion, because the cervical pedicle is small and is adjacent laterally to the vertebral artery, medially to the spinal cord, and vertically to the nerve roots. Lateral mass screws are also reported to involve a risk of neurovascular injuries. The laminar screw method was thus thought to be useful, since arterial injuries could thus be avoided and it could also be used as a salvage modality for the previous misinsertion.  相似文献   
188.
Bicarbonate secretion occurs in almost all segments of the gastrointestinal tract. This study examined HCO(3)(-) secretion in the ileum, since it is less understood than HCO(3)(-) secretion in other intestinal segments. Mouse ileal mucosa was mounted in vitro in Ussing chambers, and the mucosal alkalinization rate (J(OH)) was determined by pH stat titration, while the mucosal side was bathed with a buffer-free solution (100% O(2)) and the serosal side with a HCO(3)(-)/CO(2)-buffered solution. The transmural potential difference (PD) was recorded. The mucosal alkalinization rate (J(OH)) was higher in the presence of mucosal Cl(-) than in its absence. Forskolin, an activator of adenylate cyclase, enhanced J(OH) and PD in both the presence and absence of mucosal Cl(-). Mucosal SO(4)(2-) also caused an increase in J(OH), although the magnitude was smaller than that induced by Cl(-). Mucosal Cl(-)-dependent J(OH) was partially inhibited by acetazolamide, 5-nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB), tenidap and probably also by niflumic acid, but not by glibenclamide, DIDS or bumetanide. The forskolin-induced J(OH) value and PD were both inhibited by NPPB and probably also by tenidap. It is concluded that HCO(3)(-)- secretion in the ileum follows a mucosal Cl(-)-dependent pathway and a cAMP-activated pathway, each being distinct from each other. The Cl(-)-dependent pathway is probably mediated by the slc26a6 anion exchanger, and possibly also by the slc26a3 anion exchanger. The cAMP-activated HCO(3)(-) secretion is probably mediated by the cystic fibrosis transmembrane conductance regulator.  相似文献   
189.
190.
Due to an increasingly ageing population, the Japanese government has promoted elderly deaths in aged care facilities. However, existing facilities were not designed to provide resident end‐of‐life care and the proportion of aged care facility deaths is currently less than 10%. Consequently, the present review evaluated the factors that promote aged care facility resident deaths in Japan from individual‐ and facility‐level perspectives to exploring factors associated with increased resident deaths. To achieve this, MEDLINE, CINAHL, Web of Science and Ichushi databases were searched on 23 January 2016. Influential factors were reviewed for two healthcare services (insourcing and outsourcing facilities) as well as external healthcare agencies operating outside facilities. Of the original 2324 studies retrieved, 42 were included in analysis. Of these studies, five focused on insourcing, two on outsourcing, seven on external agencies and observed facility/agency‐level factors. The other 28 studies identified individual‐level factors related to death in aged care facilities. The present review found that at both facility and individual levels, in‐facility resident deaths were associated with healthcare service provision, confirmation of resident/family end‐of‐life care preference and staff education. Additionally, while outsourcing facilities did not require employment of physicians/nursing staff to accommodate resident death, these facilities required visits by physicians and nursing staff from external healthcare agencies as well as residents' healthcare input. This review also found few studies examining outsourcing facilities. The number of healthcare outsourcing facilities is rapidly increasing as a result of the Japanese government's new tax incentives. Consequently, there may be an increase in elderly deaths in outsourcing healthcare facilities. Accordingly, it is necessary to identify the factors associated with residents' deaths at outsourcing facilities.  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