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   111615篇
  免费   6474篇
  国内免费   779篇
耳鼻咽喉   1672篇
儿科学   4441篇
妇产科学   2969篇
基础医学   13730篇
口腔科学   3293篇
临床医学   8817篇
内科学   23457篇
皮肤病学   2455篇
神经病学   9701篇
特种医学   4514篇
外国民族医学   23篇
外科学   17239篇
综合类   2048篇
一般理论   54篇
预防医学   5936篇
眼科学   2038篇
药学   8583篇
  4篇
中国医学   650篇
肿瘤学   7244篇
  2023年   589篇
  2022年   1156篇
  2021年   2058篇
  2020年   1376篇
  2019年   1878篇
  2018年   2429篇
  2017年   1911篇
  2016年   2068篇
  2015年   2282篇
  2014年   3044篇
  2013年   4428篇
  2012年   5727篇
  2011年   5958篇
  2010年   3801篇
  2009年   3231篇
  2008年   5227篇
  2007年   5564篇
  2006年   5377篇
  2005年   5222篇
  2004年   5641篇
  2003年   5420篇
  2002年   5446篇
  2001年   4452篇
  2000年   4320篇
  1999年   3544篇
  1998年   1312篇
  1997年   1028篇
  1996年   980篇
  1995年   866篇
  1994年   751篇
  1993年   717篇
  1992年   1897篇
  1991年   1862篇
  1990年   1567篇
  1989年   1536篇
  1988年   1368篇
  1987年   1221篇
  1986年   1218篇
  1985年   1074篇
  1984年   802篇
  1983年   713篇
  1982年   458篇
  1981年   400篇
  1979年   584篇
  1978年   433篇
  1975年   438篇
  1974年   500篇
  1973年   478篇
  1972年   442篇
  1971年   403篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Granulocyte colony-stimulating factor (G-CSF) has been used to reduce the duration and/or degree of neutropenia of different etiologies in recent years. In this study, experience with the use of G-CSF (Neupogen, Roche) after 123 courses of highly myelosuppressive chemotherapy administered to 31 (20 female, 11 male) patients with pediatric solid tumors is reported. G-CSF was initialed at a white blood cell (WBC) count of 918 ± 452/μL (100-2000), at a dose of 7.6 ± 2.3 μg/kgl/d (5-14) subcutaneously for 5.2 ± 2.4 days (2-18). G-CSF was given for afebrile neutropenia after 82 and for febrile neutropenia after 41 courses. Only in two episodes where G-CSF was given for afebrile neutropenia, fever developed. The average hospitalization period for febrile neutropenia was 9.8 ± 3.3 days (5-20). Chemotherapy could be given on scheduled time and dosage in 90% of the courses in which G-CSF was used for afebrile neutropenia. G-CSF was well tolerated. Bone pain was observed in two patients and urticaria in one patient. In conclusion, G-CSF increased the WBC count effectively, there were only two febrile episodes in 82 courses in children receiving G-CSF for afebrile neutropenia, it was well tolerated, and it was found to be feasible for use in a developing country.  相似文献   
992.
To understand further the role of trace elements in the pathogenesis of febrile convulsions, serum zinc (Zn), copper (Cu), magnesium (Mg) and CSF Zn, Cu, Mg and protein levels were measured by spectrometry in patients with febrile convulsion (n=19), bacterial meningitis (n=9), viral CNS infection (n=16) and in the control groupn=10) which consisted of children with signs of meningeal irritation due to upper respiratory tract infection but normal CSF findings. Samples were obtained within 6 h after admission to hospital. Mean serum and CSF Zn levels in the febrile convulsion group were significantly lower than in the other groups (for serum Zn: 0.66±0.03 mg/l vs 0.98±0.07 mg/l, 1.06±0.08 mg/l, 1.05±0.09 mg/lP<0.05; for CSF Zn: 22.96±1.62 g/l vs 75.47 ±6.9 g/l, 50.32±5.235 g/l, 39.85 ±2.81 g/lP<0.05). A linear relationship was established between serum Zn and CSF Zn levels (P<0.001). Mean CSF Zn, Cu and protein levels in the bacterial meningitis group were significantly higher than in the other groups (for CSF Cu 63.94±6.33 g/l vs 38.77±2.70 g/l, 35.84±3.48 g/l, 33.86±2.88 g/lP<0.05; for CSF protein 0.80 ± 0.12 g/l vs 0.22±0.02 g/l, 0.53±0.08 g/l, 0.19±0.01 g/lP<0.05). In children with meningitis, the elevation of the mean CSF Zn and Cu levels may result from the breakdown of the blood-brain barrier and subsequent leakage of trace elements and protein from serum to CSF. There was no significant difference between the four groups in terms of mean serum Mg and mean CSF Mg levels.Conclusion Serum and CSF Zn levels are decreased in children with febrile seizures. Zinc deprivation may play a role in the pathogenesis of febrile seizures.  相似文献   
993.
A case of unusual transmission by Plasmodium falciparum malaria is reported. The patient, had not been travelling outside North-West of Italy for the previous 6 months, he was not drug abuser. He had spent the last two months prior his admission, partly in his home town, an urban area in the region of Piemonte, and partly in a resort area on the Ligurian sea. Neither place has ever been associated with unusual malaria transmission. The possible transmission way is through a live vector imported from endemic area in a port terminal near a resort area.  相似文献   
994.
Purpose. To evaluate the effect of the crosslinked poly(acrylate) carbomer 934P (C934P) and its freeze-dried neutralized sodium salt (FNaC934P) as well as chitosan hydrochloride on the intestinal absorption of the peptide drug buserelin. Methods. Buserelin was applied intraduodenally in control buffer, 0.5% (w/v) C934P, 0.5% (w/v) FNaC934P, 1.5% (w/v) chitosan hydrochloride or FNaC934P/chitosan hydrochloride (1:1 (v/v)) mixture in rats. Results. All polymer preparation showed a statistically significant improvement of buserelin absorption compared to the control solution. The absolute bioavailabilities for the different polymer preparations were: control, 0.1%; 0.5% FNaC934P, 0.6%; 0.5% C934P, 2.0%; chitosan hydrochloride, 5.1% and FNaC934P/chitosan hydrochloride (1:1 (v/v)) mixture, 1.0%. The higher bioavailability with chitosan hydrochloride compared to C934P and FNaC934P indicates that for buserelin the intestinal transmucosal transport enhancing effect of the polymer plays a more dominant role than the protection against proteases such as -chymotrypsin. Conclusions. The mucoadhesive polymers carbomer 934P and chitosan hydrochloride are able to enhance the intestinal absorption of buserelin in vivo in rats, and may therefore be promising excipients in peroral delivery systems for peptide drugs.  相似文献   
995.
996.
Over the next 25 years, as populations age and tobacco consumption increases, most developing regions will likely see noncommunicable diseases become the leading causes of disability and premature mortality. The already existing problems of malnutrition and infectious diseases will remain. In this context, the World Bank is examining its role and contribution to global health. From a small start approximately 25 years ago, the Bank has greatly expanded its role in international health, population, and nutrition to become the largest single external financier of health activities in low- and middle-income countries. Many other Bank-supported activities affect health, including poverty reduction, housing, water and sanitation, and the education of girls. The Bank is also increasingly active in health policy debates, publishing numerous studies annually. Most of these studies focus upon specific countries, but some address key issues of concern to many developing countries. This article explains why the Bank continues to expand its resources devoted to health and the rationale for the changing emphasis of its activities in the field.  相似文献   
997.

Purpose

We quantified the physiological variability of clinical and pressure-flow study variables in patients with symptomatic benign prostatic enlargement.

Materials and Methods

Symptom scores were measured, and advanced urodynamic studies with pressure-flow analysis were performed in 178 patients before and 6 months after a period of watchful waiting.

Results

Patients without bladder outlet obstruction experienced significant symptomatic improvement. Symptoms in patients with obvious bladder outlet obstruction did not improve significantly. The reproducibility of mean pressure-flow variables was evident. However, there was an important intra-individual variability. Patients with obvious bladder outlet obstruction showed a significant decrease in detrusor pressure at maximal flow of 14 cm. water, a significant decrease in the urethral resistance factor of 7 cm. water and a significant decrease of 1 obstruction class on the linear passive urethral resistance relation nomogram, indicating less severe bladder outlet obstruction.

Conclusions

Mean differences among therapy groups must be regarded critically, especially when the differences are slight and possibly within physiological variability.  相似文献   
998.
In 33 subjects receiving long-term haemodialysis sonographic examination of shoulders, hips and knees was performed. Changes of both joints and periarticular soft tissues were found in 60 shoulders, 16 hips and 42 knees. In the shoulder besides the presence of tenosynovitis and bursitis, even significant thickening of rotator cuff and increased distance between capsule and bone in transascellar scan were found. Also, in the hip the distance between capsule and bone was significantly increased. In the knee effusion was present in 14 cases and synovial hypertrophy in 20. Articular femoral cartilage was significantly thinned. Results obtained suggest the hypothesis of the presence of an important inflammatory component in the pathogenesis of arthropathy related to haemodialytic treatment. The production of cytokines by mononuclear cells stimulated by -2 microglobulin may cause the inflammatory response. Sonographic findings of alterations in 42 symptomless joints show the importance of this diagnostic method to begin an early therapy.Correspondence to: G. Coari  相似文献   
999.
A prevalence survey of movement disorders, epilepsy, hypertension and smoking was undertaken in Vejer de la Frontera, Southern Spain in 1988. A validated screening instrument designed for door-to-door tracing of specific disorders was used. Neurological diagnoses were based on: (1) direct anamnesis and examination by a senior neurologist; (2) perusal of existing medical records; and (3) in a proportion of cases, a hospital-based complementary study. This experience suggests that, while door-to-door surveys of neurological disorders have focused on multiple major outcomes: (1) scientific and logistic reasons can exist for screening for specific neurological disorders, and (2) scientific and public health-related interventional objectives can be combined advantageously when such costly investigations are conducted.  相似文献   
1000.
The case of a young patient with left accessory nerve paralysis is reported. He had slight tilting of the head to the right side, developed over a period of about 6 months. On neurological examination hypotrophy of the left sternocleidomastoid and trapezius muscles was observed. MRI and MR-angiography imaged the presence of a neurovascular compression between the medulla oblungata, at the level of the nerve entry zone, and a vessel loop of an elongated left vertebral artery. In spite of the absence of a surgical demonstration it is our opinion that the neurovascular conflict is the cause of the accessory nerve palsy.  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