全文获取类型
收费全文 | 9526篇 |
免费 | 444篇 |
国内免费 | 86篇 |
专业分类
耳鼻咽喉 | 88篇 |
儿科学 | 150篇 |
妇产科学 | 123篇 |
基础医学 | 1102篇 |
口腔科学 | 184篇 |
临床医学 | 594篇 |
内科学 | 2810篇 |
皮肤病学 | 232篇 |
神经病学 | 543篇 |
特种医学 | 284篇 |
外科学 | 1470篇 |
综合类 | 59篇 |
一般理论 | 1篇 |
预防医学 | 351篇 |
眼科学 | 123篇 |
药学 | 633篇 |
中国医学 | 11篇 |
肿瘤学 | 1298篇 |
出版年
2023年 | 44篇 |
2022年 | 101篇 |
2021年 | 203篇 |
2020年 | 120篇 |
2019年 | 145篇 |
2018年 | 232篇 |
2017年 | 178篇 |
2016年 | 189篇 |
2015年 | 219篇 |
2014年 | 297篇 |
2013年 | 359篇 |
2012年 | 579篇 |
2011年 | 677篇 |
2010年 | 357篇 |
2009年 | 290篇 |
2008年 | 527篇 |
2007年 | 611篇 |
2006年 | 575篇 |
2005年 | 511篇 |
2004年 | 536篇 |
2003年 | 501篇 |
2002年 | 534篇 |
2001年 | 152篇 |
2000年 | 171篇 |
1999年 | 209篇 |
1998年 | 155篇 |
1997年 | 115篇 |
1996年 | 133篇 |
1995年 | 113篇 |
1994年 | 96篇 |
1993年 | 90篇 |
1992年 | 125篇 |
1991年 | 97篇 |
1990年 | 86篇 |
1989年 | 93篇 |
1988年 | 78篇 |
1987年 | 64篇 |
1986年 | 50篇 |
1985年 | 56篇 |
1984年 | 40篇 |
1983年 | 26篇 |
1982年 | 25篇 |
1981年 | 21篇 |
1980年 | 20篇 |
1979年 | 33篇 |
1978年 | 17篇 |
1977年 | 27篇 |
1976年 | 18篇 |
1975年 | 21篇 |
1969年 | 17篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Elderly onset rheumatoid arthritis (RA) is difficult to diagnose definitively when the patients note their first symptoms of arthritis above the age of 75 years old. In this report, we reviewed the clinical features of elderly onset RA and its diagnosis. The subjects included 4 females, aged 78, 83, 84 and 93 years, respectively. The onsets were abrupt in 2 cases and more slowly arriving in the other 2. Shoulder joints and wrist joints were involved in all cases. Knee joints, finger joints and foot joints were involved in 3 cases and the elbow was involved in one case. Anti-RA treatment quickly attenuated the acute and severe arthritis and brought down the high CRP level associated with vivid inflammatory activity of RA. The RAPA value was very high in all but one of the cases. Severe destructive findings in radiography was undetectable in the major joints (e.g. shoulder, hip and knee joints). Radiographic findings in wrist and finger joints were also very difficult to differentiate from arthrosis and osteoporosis. On the other hand, RA involvement in the cervical spine was certain in the radiographs; 1 case had anterior atlantoaxial subluxation and 2 cases had subaxial intervertebral erosion. Pathological radiographic findings in the cervical spine are useful for the diagnosis of elderly onset RA. 相似文献
22.
In our miniature swine model simulating operating room brain retraction, we investigated the effects of mannitol plus nimodipine on cerebral blood flow (CBF) and evoked potentials (EP) ipsilateral and contralateral to retraction, in comparison with either agent alone, during both normoventilation and hyperventilation. We here report results in 27 animals with intravenous mannitol (2 g kg-1 over 15 min) and/or nimodipine (1 microgram kg-1 min-1 constant infusion). Mannitol plus nimodipine was superior both to controls and to either mannitol alone or nimodipine alone in preserving EP amplitude ipsilateral to retraction during both normoventilation and hyperventilation. Mannitol alone was effective in normoventilation at preserving EP, while nimodipine alone was effective in hyperventilation. No significant asymmetries in CBF or EP were seen with mannitol plus nimodipine in either normoventilation or hyperventilation. By five minutes postretraction CBF had returned to preretraction values for all groups, and EP amplitude had returned also except for hyperventilated controls. In this model of brain retraction, mannitol plus nimodipine is superior to either agent alone in maintaining both CBF and EP when normoventilation and hyperventilation are employed. The results are discussed in terms of the possible mechanisms for the different and complementary effects of mannitol and nimodipine. 相似文献
23.
K. Nakamura T. Saito T. Nishiwaki K. Ueno M. Nashimoto Y. Okuda Y. Tsuchiya R. Oshiki K. Muto M. Yamamoto 《Osteoporosis international》2006,17(8):1202-1207
Introduction A few epidemiologic studies have comprehensively attempted to identify risk factors for low bone mineral density (BMD) in elderly Asian women. The purpose of this study was to identify demographic, lifestyle, and biochemical factors correlated with BMD in elderly Japanese women 69 years of age and over.Methods The study design was cross-sectional. The subjects were 583 ambulatory women aged 69 years and over, and their average age was 74.3 (SD 4.4) years. Predictor variables were age, reproductive history, anthropometric indices, grip strength, calcium intake, lifestyle information, and serum 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D (1,25(OH)2D), osteocalcin (OC), and undercarboxylated osteocalcin (ucOC) values. The outcome variable was forearm BMD measured with a DTX-200 osteometer.Results Simple linear regression analyses showed that BMD was significantly positively associated with body height, weight, body mass index, grip strength, serum albumin concentration, and “housework,” and negatively associated with age, years since menopause, age at menarche, number of children, serum 1,25(OH)2D concentration, serum OC concentration, and ucOC concentration. The stepwise multiple regression analysis showed that weight (β=0.00316, SE=0.00028, R2=0.180), age (β=−0.00321, SE=0.00050, R2=0.108), log-transformed serum OC (β=−0.0445, SE=0.0064, R2=0.053), log-transformed serum 1,25(OH)2D (β=−0.0401, SE=0.0074, R2=0.050), “farmwork” (β=0.00904, SE=0.00426, R2=0.005), and serum 25(OH)D concentration (β=0.000281, SE=0.000120, R2=0.003) were significantly associated with BMD.Conclusion It was concluded that body weight is a major predictor of forearm BMD among the factors measured in this study in independent Japanese women 69 years of age and over and that serum 1,25(OH)2D concentration may be associated with cortical BMD. Maintenance of body weight is very important for maintaining BMD in this population, unless a large weight aggravates obesity-related diseases. A follow-up study is needed to confirm these findings. 相似文献
24.
25.
Ascorbic acid 2-O-alpha-glucoside (AA-2G) is a stable ascorbate derivative which has vitamin C activity in vivo and in vitro. We studied whether AA-2G exerts a prooxidant action in cultured fibroblasts from chick embryo and human skin, as does ascorbic acid. At concentrations of 0.1-1.0 mM, ascorbic acid markedly reduced the viable cell number of low density cultures within 24 hr, whereas AA-2G had no such effect. The ascorbate cytotoxicity was dependent on the cell density at the time of its addition and it was characteristic of low density cultures. This cytotoxicity was completely prevented by catalase and partially by an Fe3+ ion chelator, desferrioxamine. In the early culture stage at which a morphological change in the fibroblasts began to occur, intracellular ascorbate concentrations in low density cultures after addition of ascorbic acid were much higher than in high density cultures. However, at the same concentrations, AA-2G did not cause an elevation even in low density cultures and it was also effective on collagen synthesis at high and medium densities. These results suggest that the abnormally accumulated ascorbic acid in the cells cultured at low density possibly amplifies the generation of oxygen radicals through the reduction of Fe3+ ions and subsequent oxidative reactions, leading to cell death. Therefore, it is concluded that AA-2G which supplies an adequate amount of ascorbic acid during culture period is a bioavailable ascorbate source without cytotoxicity. 相似文献
26.
Kazuhiko Suzuki Hiroshi Tanaka Satoshi Kaneko Motoi Nishi Shin Teramoto Susumu Itoh Shosaku Abe 《The Journal of asthma》2003,40(3):243-250
The relation between smoking and risk of asthma has been well-examined; however little attention has been paid to the correlation between smoking and asthma symptoms. The aims of this study were to examine respiratory symptoms in asthmatics with a highly prevalent use of inhaled corticosteroid (ICS) and to assess the effects of smoking and its cessation. A cross-sectional study of pulmonologist-based 3197 asthmatics (men 45.2%, ages 20-97) was performed using a questionnaire about smoking habits, the incidence and frequency of symptoms (sputum, cough and wheezing, night symptoms, and shortness of breath), physical activity interference, and medication. Although 81.4% of the patients used ICS according to the international guideline, 14.9% had activity interference, and daily symptoms remained in 43.3%. At the time of the questionnaire, 21.6% were current and 25.1% were ex-smokers. In multiple logistic regression analysis, the factors of significance (p < 0.0001) were (1) smoking; for all four symptoms, (2) age and duration of asthma; for shortness of breath. Current smokers were at a risk of sputum (age-adjusted odds ratio 2.32 [95% confidence interval 1.73-3.11]; 2.09 [1.57-2.79]), of cough and wheezing (2.38 [1.81-3.14]; 1.78 [1.35-2.36]), of night symptoms (1.95 [1.41-2.60]; 1.47 [1.09-1.98]), and of shortness of breath (1.70 [1.26-2.28]; 1.30 [0.97-1.75]) in men and women, respectively. These ratios in ex-smokers decreased to the level similar to nonsmokers. Although 81.4% of asthmatic patients used ICS, 43.3% complained of daily respiratory symptoms, especially sputum. It is suggested that the effects of ICS on asthma symptoms may be interfered with by smoking and therefore more emphasis should be placed on cessation of smoking. 相似文献
27.
Kazuhiko Sonoyama Haruaki Ninomiya Osamu Igawa Yasuhiro Kaetsu Yoshiyuki Furuse Toshihiro Hamada Junichiro Miake Peili Li Yasutaka Yamamoto Kazuhide Ogino Akio Yoshida Shin-ichi Taniguchi Yasutaka Kurata Satoshi Matsuoka Toshio Narahashi Goshi Shiota Yoshihisa Nozawa Hiroaki Matsubara Masatsugu Horiuchi Yasuaki Shirayoshi Ichiro Hisatome 《Hypertension research》2006,29(11):923-934
We examined the effects of angiotensin II (Ang II) on inward rectifier K+ currents (IK1) in rat atrial myocytes. [125I]Ang II-binding assays revealed the presence of both Ang II type 1 (AT1) and type 2 (AT2) receptors in atrial membrane preparations. Ang II inhibited IK1 in isolated atrial myocytes with an IC50 of 46 nmol/l. This inhibition was abolished by the AT, antagonist RNH6270 but not at all by the AT2 antagonist PD123319. Treatment of cells with pertussis toxin or a synthetic decapeptide corresponding to the carboxyl-terminus of Gialpha-3 abolished the inhibition by Ang II, indicating the role of a Gi-dependent signaling pathway. Accordingly, Ang II failed to inhibit IK1 in the presence of forskolin, dibutyryl-cAMP or protein kinase A catalytic subunits. In spite of the increased binding capacities for [125I]Ang II, Ang II failed to affect IKI in cells from spontaneously hypertensive rats (SHR). AT, immunoprecipitation from atrial extracts revealed decreased amounts of Gialpha-2 and Gialpha-3 proteins associated with this receptor in SHR as compared with controls. The reduced coupling of AT, with Gialpha. proteins may underlie the unresponsiveness of atrial IK1 to Ang II in SHR cells. 相似文献
28.
Histological, immunohistochemical, and electron microscopic evidence of an extracellular, or ghost Pick body has been found in the granular cell layer and, rarely, in the pyramidal cell layer of the hippocampus of an autopsy case of Pick's disease. The ghost Pick body appeared as a blurred, weak argyrophilic mass in the neuropil, and it was composed of accumulated fibrillary structures, 13 nm in diameter, intermingled with glial filament bundles. These ghost Pick bodies did not react with anti-tau and antiubiquitin antibodies, but did react weakly with antiglial fibrillary acidic protein antibody, whereas intracytoplasmic Pick bodies were strongly immunolabeled with anti-tau but only weakly with anti-ubiquitin anti-bodies. These results suggest that the Pick body is discharged into the neuropil after destruction of the mother neuron, loses its immunoreactivity to certain tau and ubiquitin antibodies during this process (thereby inducing a glial reaction) and remains in the neuropil as a ghost Pick body. 相似文献
29.
Kazuhiko Nishizaki Toshio Seki Takehisa Abe 《Annals of thoracic and cardiovascular surgery》2006,12(4):293-296
This reports a case of a 68-year-old woman who had undergone coronary artery bypass 5 years previously. Magnetic resonance angiography (MRA) revealed that the ascending aorta was dilated to about 8 cm in diameter, with type A dissection, and with a patent left internal thoracic artery (LITA) graft to the left anterior descending artery (LAD). Angiography at the ascending aorta did not reveal a coronary artery, nor did it show the sequential saphenous vein graft (SVG) to the obtuse marginal and posterolateral branches. Although the risk of surgical treatment via repeat median sternotomy was very high, we successfully performed the reoperation using profound hypothermic circulatory arrest. The dissection in the mediastinum was facilitated by a sternum retractor for ITA-graft dissection, intraoperative surface echocardiography, and ultrasonic scalpel, with a widely opened bilateral pleural cavity. Furthermore, assuming that most of the myocardium was maintained by perfusion from the in-situ, patent, ITA graft, it was thought that cardioplegia was not necessary during profound hypothermic circulation. 相似文献
30.
Manabu Muto Mitsuhiro Fujishiro Yoshitaka Sato Yasumasa Niwa Mitsuru Kaise Mototsugu Kato Kaiyo Takubo 《Digestive endoscopy》2007,19(Z1):S153-S155
Optical technological innovations enable us to visualize cellular nuclei endoscopically. Herein is described a protocol design for a multicenter study for the ex vivo evaluation of endocytoscopy. The present study was performed by the Endoscopy Forum Japan study group. 相似文献