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   6544篇
  免费   310篇
  国内免费   18篇
耳鼻咽喉   36篇
儿科学   180篇
妇产科学   107篇
基础医学   839篇
口腔科学   298篇
临床医学   499篇
内科学   1305篇
皮肤病学   92篇
神经病学   521篇
特种医学   331篇
外科学   1124篇
综合类   42篇
一般理论   5篇
预防医学   434篇
眼科学   99篇
药学   514篇
中国医学   3篇
肿瘤学   443篇
  2022年   47篇
  2021年   93篇
  2020年   68篇
  2019年   94篇
  2018年   103篇
  2017年   111篇
  2016年   128篇
  2015年   109篇
  2014年   198篇
  2013年   306篇
  2012年   390篇
  2011年   406篇
  2010年   231篇
  2009年   239篇
  2008年   372篇
  2007年   358篇
  2006年   395篇
  2005年   372篇
  2004年   330篇
  2003年   339篇
  2002年   324篇
  2001年   66篇
  2000年   72篇
  1999年   80篇
  1998年   90篇
  1997年   78篇
  1996年   81篇
  1995年   75篇
  1994年   65篇
  1993年   59篇
  1992年   55篇
  1991年   73篇
  1990年   70篇
  1989年   63篇
  1988年   67篇
  1987年   56篇
  1986年   45篇
  1985年   63篇
  1984年   48篇
  1983年   55篇
  1982年   58篇
  1981年   39篇
  1980年   39篇
  1979年   37篇
  1978年   42篇
  1977年   38篇
  1976年   23篇
  1975年   28篇
  1973年   27篇
  1971年   20篇
排序方式: 共有6872条查询结果,搜索用时 0 毫秒
61.
Summary We describe the presumably first intentional ABO‐incompatible deceased‐donor kidney and pancreas transplantation with a severe antibody‐mediated rejection during a rebound of isoagglutinins. Rejection was successfully treated with eculizumab, which inhibits the terminal pathway of complement. Complement analysis (C3, C3d,g, and a modified assay of classical complement‐related hemolytic function) documented complement activation and confirmed that eculizumab completely blocked complement function. At 6 months, the patient had normal kidney and pancreas function, and histological evaluations revealed no evidence of sustained graft damage. This successful transplantation suggests that ABO barriers can safely be overcome without extensive preconditioning, when the complement inhibitor eculizumab is included.  相似文献   
62.
Degenerative disk disease is a strong etiologic risk factor of chronic low back pain (LBP). A multidisciplinary approach to treatment is often warranted. Patient education, medication, and cognitive behavioral therapies are essential in the treatment of chronic LBP sufferers. Surgical intervention with a rehabilitation regime is sometimes advocated. Prognostic factors related to the outcome of different treatments include maladaptive pain coping and genetics. The identification of pain genes may assist in determining individuals susceptible to pain and in patient selection for appropriate therapy. Biologic therapies show promise, but clinical trials are needed before advocating their use in humans.  相似文献   
63.
A major obstacle for the transplantation of neural stem cells (NSCs) into the lesioned spinal cord is their predominant astrocytic differentiation after transplantation. We took advantage of this predominant astrocytic differentiation of NSCs and expressed the paradigmatic beneficial neural cell adhesion molecule L1 in radial glial cells and reactive and nonreactive astrocytes as novel cellular vehicles to express L1 under the control of the promoter for the human glial fibrillary acidic protein (GFAP-L1 NSCs). Behavioral analysis and electrophysiological H-reflex recordings revealed that mice transplanted with GFAP-L1 NSCs showed enhanced locomotor recovery in comparison to mice injected with wild type (WT) NSCs or control mice injected with phosphate-buffered saline (PBS). This functional recovery was further accelerated in mice transplanted with L1-expressing radial glial cells that had been immunoisolated from GFAP-L1 NSCs (GFAP-L1-i cells). Morphological analysis revealed that mice grafted with GFAP-L1 NSCs exhibited increased neuronal differentiation and migration of transplanted cells, as well as increased soma size and cholinergic synaptic coverage of host motoneurons and increased numbers of endogenous catecholaminergic nerve fibers caudal to the lesion site. These findings show that L1-expressing astrocytes and radial glial cells isolated from GFAP-L1 NSC cultures represent a novel strategy for improving functional recovery after spinal cord injury, encouraging the use of the human GFAP promoter to target beneficial transgene expression in transplanted stem cells.  相似文献   
64.
Study Type – Preference (prospective cohort) Level of Evidence 4 What’s known on the subject? and What does the study add? Functional gastrointestinal symptoms and problems are common after radical cystectomy with urinary diversion. This study adds new important epidemiological data on this group of symptoms.

OBJECTIVE

  • ? To describe and compare long‐term defecation disturbances in patients who had undergone a cystectomy due to urinary bladder cancer with non‐continent urostomies, continent reservoirs and orthotopic neobladder urinary diversions.

PATIENTS AND METHODS

  • ? During their follow‐up we attempted to contact all men and women aged 30–80 years who had undergone cystectomy and urinary diversion at seven Swedish hospitals.
  • ? During a qualitative phase we identified defecation disturbances as a distressful symptom and included this item in a study‐specific questionnaire together with free‐hand comments. The patients completed the questionnaire at home.
  • ? Outcome variables were dichotomized and the results are presented as relative risks with 95% confidence interval.

RESULTS

  • ? The questionnaire was returned from 452 (92%) of 491 identified patients. Up to 30% reported problems with the physiological emptying process of stool (bowel movement, sensory rectal function, awareness of need for defecation, motoric rectal and anal function, straining ability).
  • ? A sense of decreased straining capacity was reported by 20% of the men and women with non‐continent urostomy and 14% and 8% of those with continent reservoirs and orthotopic neobladders, respectively.

CONCLUSIONS

  • ? Of the cystectomized individuals 30% reported problems with the physiological emptying process of stool (bowel movement, sensory rectal function, awareness of need for defecation, motoric rectal and anal function, straining ability).
  • ? Those wanting to improve the situation for bladder cancer survivors may consider communicating before surgery the possibility of stool‐emptying problems, and asking about them after surgery.
  相似文献   
65.
66.
Cystinuria is a rare hereditary disease resulting in recurrent stone formation and the need for repeated invasive interventions. So far, two responsible genes have been identified which encode the two transporters, rBAT and b0,+AT forming a heterodimer to transport cystine in proximal tubular cells (PTC) and whose defect results in increased excretion of cystine. A human cell line mimicing the phenotype of cystinuria in vitro is yet to be developed. Human kidney (HK)-2 is a PTC line derived from normal HK. After determining the presence of rBAT gene by RT-PCR and Western blot analysis, radioactively labeled cystine (S35) was used to evaluate the functional presence of the amino acid transport in HK-2 cells when cultured in vitro. To achieve a cystinuria type I phenotype in HK-2 cells, the rBAT gene was silenced using antisense oligonucleotides complimentary to human rBAT mRNA. The reduced transport activity of cystine was then determined by radiolabeled cystine uptake measurements. RT-PCR and Western blot confirmed the expression of the rBAT gene in HK-2 cells. Considerable transport of the radio labeled cystine was observed in HK-2 cells and was linearly dependent on the incubation time with the amino acid. The cystine transport in rBAT knockdown cells after incubation with antisense oligonucleotides was significantly lower compared to control (0.76 vs. 0.98%; P = 0.0008), proving a transient knock-down of the rBAT gene. This study demonstrates the presence of the b0,+ amino acid transport system in human proximal tubular HK-2 cells when cultured in vitro. Inhibition of this transport system is possible by using antisense technology. A permanent inhibition of the cystine transport, based on our model, would be useful for the development and evaluation gene therapeutic approaches. Gunnar Wendt-Nordahl, Sreedhar Sagi contributed equally to this work.  相似文献   
67.
Lung transplantation (LTx) is a therapeutic option for patients with end-stage lung disease. However, the mortality rate of patients on the waiting list is high. The purpose of this study was to examine the prognostic value of cardio-pulmonary hemodynamics for death in patients awaiting LTx. Retrospectively, 177 patients with advanced lung disease accepted for LTx at Sahlgrenska University Hospital from January 1990 through December 2003 were studied. Patient demographics, pulmonary function tests, gas exchange and hemodynamic variables were included in the analysis. Death while awaiting LTx was the primary endpoint for all analyses. Mean age was 49 +/- 9 years. Main diagnoses were alpha 1 antitrypsin deficiency (n = 56), chronic obstructive pulmonary disease (n = 61), cystic fibrosis (n = 14) and interstitial lung disease (n = 46). Thirty patients died (17%). LTx was performed in 143 cases. By univariate analyses, forced vital capacity (FVC) % of predicted, pulmonary vascular resistance (PVR) and diagnosis were associated with risk for death. In multivariate analysis PVR (HR, 1.22; 95% CI, 1.06-1.41; P = 0.006) and FVC% of predicted (HR, 0.97; 95% CI, 0.94-0.99; P = 0.01) were independently associated with death. Patients with increased PVR and a lower FVC % of predicted awaiting LTx should be considered for a higher organ allocation priority. Assessment of pulmonary hemodynamics needs to be considered during evaluation for LTx.  相似文献   
68.

Background  

Hip dislocation in children with cerebral palsy (CP) is a common and severe problem. The dislocation can be avoided, by screening and preventive treatment of children with hips at risk. The aim of this study was to analyse the characteristics of children with CP who develop hip displacement, in order to optimise a hip surveillance programme.  相似文献   
69.
Gene polymorphism association studies in dialysis: vascular access   总被引:2,自引:0,他引:2  
Complications of the vascular access site for hemodialysis are a major cause of morbidity, suboptimal dialysis, and hospitalization. Vascular access for dialysis that is achieved by central venous catheters is associated with complications such as infection and thrombosis. Arteriovenous fistulas and grafts are also at risk for infectious complications. Further, proliferation of the venous wall with secondary thrombosis is a common pathophysiological process that leads to vascular access dysfunction. Genetic polymorphisms that contribute to vascular access failure are found among factors of the coagulation cascade, and host mediators that induce endothelial dysfunction as well as vessel wall proliferation. The two most common mutations of coagulation factors seem to influence the risk of central venous catheter and fistula thrombosis. Indeed, both the single nucleotide polymorphism of the factor V gene at amino acid position 506 (factor V Leiden mutation) and the prothrombin 20210 polymorphism have been associated with thrombotic complications of the vascular access. Among the endothelium-directed factors, a polymorphism of the methylene tetrahydrofolate reductase gene coding for an enzyme that degrades the endothelium toxic product homocysteine, has been associated with fistula failure. While the angiotensin converting enzyme polymorphism does not seem to be associated with vascular access complications, polymorphisms of the profibrogenic cytokine transforming growth factor-beta1 are associated with the prognosis of native arteriovenous fistulae. The role of pro- and anti-inflammatory cytokine gene polymorphisms as prognostic factors for vascular access is yet to be clearly defined.  相似文献   
70.
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