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   107208篇
  免费   6038篇
  国内免费   650篇
耳鼻咽喉   1042篇
儿科学   3494篇
妇产科学   2456篇
基础医学   15403篇
口腔科学   3934篇
临床医学   9724篇
内科学   24129篇
皮肤病学   2711篇
神经病学   10472篇
特种医学   2489篇
外国民族医学   1篇
外科学   9572篇
综合类   395篇
一般理论   48篇
预防医学   10722篇
眼科学   1721篇
药学   7490篇
中国医学   418篇
肿瘤学   7675篇
  2024年   122篇
  2023年   1031篇
  2022年   2218篇
  2021年   3665篇
  2020年   2294篇
  2019年   3083篇
  2018年   3501篇
  2017年   2671篇
  2016年   3107篇
  2015年   3432篇
  2014年   4513篇
  2013年   5889篇
  2012年   8955篇
  2011年   9300篇
  2010年   5069篇
  2009年   4264篇
  2008年   7400篇
  2007年   7390篇
  2006年   6801篇
  2005年   6335篇
  2004年   5696篇
  2003年   5064篇
  2002年   4558篇
  2001年   535篇
  2000年   378篇
  1999年   590篇
  1998年   794篇
  1997年   647篇
  1996年   547篇
  1995年   451篇
  1994年   431篇
  1993年   352篇
  1992年   290篇
  1991年   193篇
  1990年   193篇
  1989年   180篇
  1988年   172篇
  1987年   145篇
  1986年   162篇
  1985年   112篇
  1984年   135篇
  1983年   129篇
  1982年   156篇
  1981年   115篇
  1980年   123篇
  1979年   71篇
  1978年   77篇
  1977年   71篇
  1976年   59篇
  1974年   52篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
71.
72.
Zusammenfassung Anamnese und Diagnostik: Ein 75-jähriger Patient wies neben unspezifischen anamnestischen Symptomen (Appetitverlust, Merkfähigkeitsstörung und Muskelschwäche) klinisch diskrete Beinödeme, abgeschwächte Muskeleigenreflexe und eine deutliche Gedächtnisstörung auf. Aufgrund einer euvolämischen, laborchemisch hypoosmolaren Hypoatriämie und eines Urinnatriums im Normbereich wurde als Arbeitsdiagnose von einem Syndrom der inadäquaten ADH-Sekretion (SIADH) ausgegangen. Während sich weder in der Anamnese noch in den folgenden Untersuchungen eine dem SIADH zugrunde liegende Pathologie eruieren ließ, ergab sich in den weiteren Laboruntersuchungen der Befund einer ausgeprägten Hypothyreose. Die Hyponatriämie bei Hypothyreose spiegelt eine Komponente der renalen Funktionsstörung bei Schilddrüsenhormonmangel wider. Therapie und Verlauf: Nach Flüssigkeitsrestriktion und Hormonsubstitution erreichte der Patient schnell normale Natriumwerte und zeigte eine deutliche Besserung seiner kognitiven Fähigkeiten. Schlussfolgerung: Als Schlussfolgerung aus dieser Kasuistik wird Zurückhaltung bei der Diagnose eines SIADH empfohlen, bevor nicht eine sorgfältige Untersuchung des Nebennieren- und Schilddrüsenhormonstatus erfolgt ist. Abstract Case History and Diagnosis: A 75-year-old male patient presented with a history of anorexia, muscle weakness, and increasing memory loss. He had mild pedal edema and decreased deep tendon reflexes. As the laboratory tests showed hypoosmolar hyponatremia and urinary sodium within the normal range, a syndrome of inappropriate ADH secretion (SIADH) was presumed. While neither the medical history nor any of the diagnostic procedures revealed any underlying pathology explaining the SIADH, laboratory tests showed significant hypothyroidism. Hypothyroid states are associated with significant changes in renal function, one of which is hypoosmolar hyponatremia. Treatment and Course: Treatment included fluid restriction and hormone substitution and resulted in a quick correction of the hyponatremia and a clear improvement of the patient's cognitive function. Conclusion: It is concluded that the diagnosis of SIADH should only be made after thorough investigation of the adrenal and thyroid hormone status.  相似文献   
73.
ABSTRACT: A case study of the creation and implementation of a four-tier, integrated system of health care services in a sparsely populated, rural province in Argentina is described and discussed. Begun in 1970 in a diverse geographical area with a tradition of poor health status and inadequate health care resources, the provincial government set out to develop the human, physical and technological resources needed to provide a system of preventive and curative services appropriate to the health care needs of its residents. Innovative programs included training in management techniques, and epidemiological perspective of high risk, an emphasis on personnel development through a rural general medicine residency and an expanded nursing program as well as programs to attack infectious diseases, poor sanitation and dental problems were all developed in response to the distinctive features of the physical and social environment of the province. Improvements in traditional health indicators are reviewed and attributed to the program and administrative structures that were developed.  相似文献   
74.
PURPOSE: A standardized, noninvasive technique to assess healing of the mandibular distraction wound is not available. Current methods include clinical examination, plain radiography, and computed tomography. These imaging techniques are expensive and obligate the patient to serial radiation exposure. In addition, anatomic overlap and metal artifacts may obscure the distraction gap. In contrast, ultrasound has been shown to be a noninvasive, efficient, and inexpensive way to evaluate bone healing. The purpose of this study was to test the feasibility of ultrasound to evaluate an experimental mandibular distraction osteogenesis wound. MATERIALS AND METHODS: Distraction devices were placed via a submandibular incision into 24 minipigs. The protocol consisted of 0-day latency and distraction rates of 1, 2, or 4 mm/d for a 12-mm gap. The wounds were assessed in vivo after 0, 8, 16, and 24 days of neutral fixation. Ex vivo radiographs were used to estimate bone fill using a semiquantitative score. A semiquantitative ultrasound score was assigned, and the beam penetration depth was measured in millimeters. RESULTS: In all groups, clinical stability of the distraction wound increased with the duration of fixation. Plain radiographs, taken during neutral fixation, showed that the desired distraction gap was achieved and maintained. The ultrasound score increased with fixation time, whereas beam penetration depth decreased as expected. Ex vivo radiographs showed increasing bone fill score with time and paralleled the ultrasound score. CONCLUSIONS: The results of this feasibility study indicate that ultrasound is potentially useful for the assessment of bone formation in distraction osteogenesis wounds.  相似文献   
75.
PDB is genetically heterogeneous. Mutations of the sequestosome1 gene have been reported in sporadic and familial forms of Paget's in patients of French Canadian and British descent. Mutational analyses in different ethnic groups are needed to accurately investigate hereditary diseases. We describe two novel mutations of sequestosome1 in 62 Italian sporadic patients, confirming the role of the encoded protein in this disorder. INTRODUCTION: Paget's disease of bone (PDB) is a relatively common disease of bone metabolism reported to affect up to 3% of whites over 55 years of age. The disorder is genetically heterogeneous, and at present, there is scientific evidence that at least eight different human chromosomal loci are correlated with its pathogenesis. Mutations of the sequestosome1 (SQSTM1) gene were identified as responsible for most of the sporadic and familial forms of Paget in patients of French Canadian and British descent. Such mutations were located at exon 7 and 8 levels, encoding for the ubiquitin protein-binding domain (UBA) and representing a mutational hot spot area. MATERIALS AND METHODS: To verify the involvement of this gene in Italian subjects affected by PDB, we performed mutational analysis in 62 sporadic PDB cases. RESULTS: We described three different mutations at exon 8 level: P392L, already described in the French Canadian population and families predominantly of British descendent, and two novel mutations consisting of the amino acid substitutions M404V and G425R. No significant differences in the clinical history of PDB have been observed in patients with SQSTM1 mutations in respect to those without. CONCLUSIONS: Even though our findings suggest a minor involvement of the SQSTM1 gene in the pathogenesis of sporadic Italian Paget's cases, the identification of different significant mutations within the SQSTM1 gene in unrelated, but clinically similar individuals, offers extremely convincing evidence for a causal relationship between this gene and PDB. Longitudinal studies are needed to assess the penetrance of genotype/phenotype correlations. Our findings confirm the evidence of a clustered mutation area at this level in this disorder.  相似文献   
76.
Ischemia negatively affects mitochondrial function by inducing the mitochondrial permeability transition (MPT). The MPT is triggered by oxidative stress, which occurs in mitochondria during ischemia as a result of diminished antioxidant defenses and increased reactive oxygen species production. It causes mitochondrial dysfunction and can ultimately lead to cell death. Therefore, drugs able to minimize mitochondrial damage induced by ischemia may prove to be clinically effective. We analyzed the effect of carvedilol, a beta-blocker with antioxidant properties, on mitochondrial dysfunction. Carvedilol decreased levels of TBARS (thiobarbituric acid reactive substances), an indicator of oxidative stress, which is consistent with its antioxidant properties. Regarding cell death by apoptosis, although ischemia did increase caspase-8-like activity, there were no changes in caspase-3-like activity, which is activated downstream of caspase-8; this may indicate that the apoptotic cascade is not activated by 60 minutes of ischemia. We conclude that carvedilol protects ischemic mitochondria by preventing oxidative mitochondrial damage, and, by so doing, it may also inhibit the formation of the MPT pore.  相似文献   
77.
78.
An unusual association with Raynaud's phenomenon   总被引:1,自引:1,他引:0  
A 36-yr-old lady with a year of typical Raynaud's and polyarthralgiahad a normal examination other than cold peripheries and bloodpressure of  相似文献   
79.
The steady-state density and the turnover rates of D1-dopamine receptors were investigated in the striatum, nucleus accumbens, substantia nigra, and retina of adult (3-month-old) and aged (23-month-old) rats. The turnover rates were measured by monitoring the repopulation kinetics of D1-dopamine receptors labeled with [3H]-SCH 23390 after the irreversible inactivation induced by a single dose of N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ, 10 mg/kg, s.c.). In all the neural tissues examined, the repopulation of D1 dopamine receptors could be adequately described by a theoretical model that assumes a constant rate of receptor production (i.e. zero order) and a rate of degradation that is dependent on the receptor density at any time (i.e. first order). The results obtained indicate that the reduction in the density of D1-dopamine receptors in the striatum, nucleus accumbens and substantia nigra of aged rats is the result of a larger decrease in the receptor production rate (−44 to −60%) than in the receptor degradation rate (−21 to −46%). By contrast, the production rate of D1-dopamine receptors in the retina of aged rats remains unchanged, whilst the degradation rate is reduced by 25%. This results in an age-related increase in the density of D1-dopamine receptors in the rat retina.  相似文献   
80.
BACKGROUND. The results of a randomized, multicenter clinical trial with perioperative short-term antibiotic plus intravenous immunoglobulins (IVIG + A) versus antibiotic alone (A) for prevention of postoperative infections in patients at risk for sepsis undergoing surgery for colorectal cancer are presented. METHODS. The patients at risk for sepsis were selected by an original multiparametric test based on delayed-hypersensitivity skin testing and serum protein electrophoretic subfractions. This screening had shown 76% positive predictability in a previous validation assessment. Eighty patients at risk for sepsis were selected prospectively from 210 patients undergoing surgery for colorectal cancer; 43 patients were randomly assigned to the IVIG + A group and 37 to the A group. IVIG was administered on the day before operation, on the first and fifth postoperative days. RESULTS. There was a clear-cut reduction of postoperative infections in the IVIG + A group: 21 infections in 20 patients versus 37 infections in 29 patients in the A group (p less than 0.004). With regard to serum immunoglobulin (Ig) G monitoring, basal IgG levels were significantly lower in patients given IVIG + A who had postsurgical infections (p less than 0.005) compared with patients with a regular outcome, whereas the same was not true in the A group of patients. CONCLUSIONS. A significant decrease (p less than 0.001) of postoperative IgG was evidenced in the A group of patients who had infections as opposed to a significant increase (p less than 0.001) of postoperative IgG in IVIG + A patients with a normal outcome.  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