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   1308篇
  免费   68篇
  国内免费   6篇
耳鼻咽喉   5篇
儿科学   120篇
妇产科学   13篇
基础医学   154篇
口腔科学   22篇
临床医学   153篇
内科学   194篇
皮肤病学   16篇
神经病学   93篇
特种医学   61篇
外科学   148篇
综合类   15篇
一般理论   2篇
预防医学   71篇
眼科学   9篇
药学   152篇
中国医学   1篇
肿瘤学   153篇
  2023年   7篇
  2022年   9篇
  2021年   17篇
  2020年   13篇
  2019年   12篇
  2018年   17篇
  2017年   10篇
  2016年   13篇
  2015年   17篇
  2014年   35篇
  2013年   33篇
  2012年   60篇
  2011年   71篇
  2010年   37篇
  2009年   30篇
  2008年   64篇
  2007年   52篇
  2006年   60篇
  2005年   49篇
  2004年   43篇
  2003年   57篇
  2002年   43篇
  2001年   34篇
  2000年   45篇
  1999年   37篇
  1998年   22篇
  1997年   15篇
  1996年   40篇
  1995年   23篇
  1994年   19篇
  1993年   12篇
  1992年   36篇
  1991年   21篇
  1990年   25篇
  1989年   21篇
  1988年   23篇
  1987年   32篇
  1986年   16篇
  1985年   26篇
  1984年   11篇
  1983年   16篇
  1982年   12篇
  1981年   16篇
  1980年   9篇
  1979年   10篇
  1977年   11篇
  1976年   6篇
  1975年   9篇
  1973年   6篇
  1970年   7篇
排序方式: 共有1382条查询结果,搜索用时 15 毫秒
991.
Effect of different doses of nasal salmon calcitonin on bone mass   总被引:3,自引:0,他引:3  
Summary Forty postmenopausal women with a former Colles' fracture were enrolled in a 1-year study to determine the dose-effect relationship of nasal salmon calcitonin (SCT) on bone mass. They were randomized to receive either placebo, 50, 100, or 200 IU per day of SCT given as a nasal spray. The rate of change in the bone mineral content of the lumbar spine was 0.7, 0.2, 1.1, and 2.0 gHA per year, respectively, and the rate of change in the bone mineral content in the forearm was −0.4, −0.1, 0.0, and −0.1 AU per year, respectively. The rate of change in the bone mineral content of the lumbar spine in patients receiving 200 IU of SCT per day differed significantly from zero (P<0.01). Except for one patient, who experienced intolerable nausea, no systemic side effects were observed. Seven patients withdrew, two patients from nasal intolerance to the spray. These preliminary data suggest that SCT given by the nasal route has a positive and dose-dependent effect on spinal bone mass, but affects forearm bone mass only minimally.  相似文献   
992.
993.
Metabotropic glutamate receptors (mGluRs) operate via the phosphoinositide second messenger cascade and have various modulatory effects on central neurones. 2-Amino-3-phosphonopropionate (AP3) has been proposed as a selective antagonist of mGluR and used to explore the physiological functions of mGluR. We have compared the effects of mGluR agonists in the presence and absence of AP3 using intracellular recording from CA1 pyramidal neurones in rat hippocampal slices. Two mM D,L-AP3 or 1 mM L-AP3 did not cause any detectable change in the effects of mGluR agonists trans-1-amino-cyclopentyl-1,3-dicarboxylate (t-ACPD) or quisqualate. These agonists still induced depolarization, inhibition of the slow after-hyperpolarization and slowing of the spike repolarization. The results argue against AP3 being an antagonist of postsynaptic mGluRs.  相似文献   
994.
Sixty-three patients with advanced cancer underwent greater than or equal to 5,000 cGy combined with Concentric Coil magnetic-induction localized hyperthermia. Tumor regression (CR + PR) was compared to thermal dose received, incorporating the premise that hyperthermia response is a function of time as well as temperature. A computer program was developed (after Sapareto and Dewey [2]) which stored minimum tumor temperatures recorded spatially and temporally during treatment and correlated response with T43 (equivalent minutes at 43 degrees C during the first treatment) and CT43 (cumulative T43, computed by multiplying T43 by the actual number of identical subsequent treatments received during the course of therapy). Those who responded--N = 46 (73%)--had significantly higher median thermal doses than those who did not respond. Comparison of T43 and CT43 thermal dose values between responders and nonresponders was significantly different at p values of 0.05 and 0.04, respectively. The data indicate that magnetic-induction hyperthermia and high-dose XRT was an effective treatment combination in advanced disease and that tumor response improved as thermal dose increased.  相似文献   
995.
Endothelial nitric oxide synthase variants in cystic fibrosis lung disease   总被引:4,自引:0,他引:4  
Variants in the genes encoding for the nitric oxide synthases may act as disease modifier loci in cystic fibrosis, affecting both an individual's nitric oxide level and pulmonary function. In this study, the 894G/T variant in exon 7 of the endothelial nitric oxide synthase gene was related to exhaled nitric oxide and pulmonary function in 70 cystic fibrosis patients who were aged 14.8 +/- 6.9 years (mean +/- SD), with a FEV1 of 69.4 +/- 24.8% predicted. Although there was no association between endothelial nitric oxide synthase genotypes and exhaled nitric oxide in males, nitric oxide levels were significantly higher in female cystic fibrosis patients with an 894T mutant allele, compared with female patients homozygous for the 894G wild-type allele (7.0 +/- 4.4 versus 3.6 +/- 1.9 parts per billion, p = 0.02). Furthermore, in female patients, colonization of airways with Pseudomonas aeruginosa was significantly (p < 0.05) less frequent when carrying an 894T mutant allele as compared with wild type. These data suggest that the 894T variant in the endothelial nitric oxide synthase gene is associated with increased airway nitric oxide formation in female cystic fibrosis patients, possibly affecting colonization of airways with P. aeruginosa.  相似文献   
996.
Hypereosinophilia can be related to various diseases; when it occurs without an obvious cause it is called idiopathic hypereosinophilic syndrome (IHES). We describe a patient with increasing eosinophilia, which in spite of extensive diagnostic procedures initially remained unexplained. However, during follow-up it became apparent that this patient had a lethal enteropathy-associated T lymphoma (EATL) causing the hypereosinophilia.  相似文献   
997.
To define the roles of the calmodulin-stimulated adenylyl cyclases (AC1 and AC8) in morphine-induced analgesia, tolerance, physical dependence, and conditioned place preference, we used mice having targeted disruptions of either the AC1 or AC8 genes or both genes [double knockout mice (DKO)]. Mice lacking either AC1 or AC8 genes or DKO did not differ from wild-type mice in short-term antinociceptive responses to morphine measured in the tail-flick analgesia assay. Morphine tolerance that developed immediately within 3 h of morphine administration (10 mg/kg s.c.) was significantly attenuated in DKO mice and AC8 single knockout mice. Tolerance induced continually by daily injections of morphine (10 mg/kg s.c.) was also reduced in DKO mice. In DKO mice continually treated with morphine, there was a significant reduction in withdrawal behaviors, including reduced wet-dog shakes and forepaw tremor after naloxone injection (10 mg/kg i.p.). Morphine produced hyperlocomotion and conditioned place preference in wild-type mice, whereas DKO mice displayed significantly less hyperlocomotion and conditioned place preference. Furthermore, the significant increase in phosphorylated cAMP-response element binding protein (CREB) staining in ventral tegmental area induced by long-term morphine treatment was not evident in DKO mice, suggesting that CREB activation by morphine requires cAMP generated by AC1 and AC8. These results support the hypothesis that calmodulin-stimulated adenylyl cyclases are important mediators of the neuronal responses to morphine.  相似文献   
998.
The 5-year relative survival from breast cancer in Denmark is 10 percentage points lower than in Sweden. This difference has been demonstrated previously as being caused partly by more involved lymph nodes and larger tumours in Denmark. Sweden has had nationwide mammography-screening coverage since 1991, whereas this is still in its infancy in Denmark. In the search for an explanation for the remaining survival difference, patient delay was a likely candidate. This study compared patient delay and mammography-detection between two national regions. Data on patient delay and mammography were obtained from hospital records from 1989 and 1994, and analysed using Cox proportional hazard analysis of death within the first 5 years, with the factors age, country, delay/mammography detection and established patho-anatomic variables. A comparison of patient delay and mammography detection in 1989 and 1994 showed more mammography-detected tumours in south Sweden and more women with long delay in east Denmark. Mammography detection, but not long patient delay, had a significant effect on the death hazard when adjusting for patho-anatomic risk factors. The hazard ratio was not eliminated in 1989, but in 1994, the hazard ratio between east Denmark and south Sweden was reduced from 1.3 to 1.1. In conclusion, patient delay did not appear to have any effect on 5-year survival when adjusting for patho-anatomic factors, but tumour detection by mammography affected survival favourably and partly explained the survival difference between east Denmark and south Sweden.  相似文献   
999.
Many advanced molecular imaging agents are currently being investigated preclinically. Especially, liposomes, have proven to be very promising carrier systems for diagnostic agents for use in single-photon emission computed tomography (SPECT) or magnetic resonance imaging (MRI), as well as for therapeutic agents to treat diseases such as cancer. In this study, nanosized liposomes were designed and labeled with the radionuclides, holmium-166 (both a beta- and gamma-emitter and also highly paramagnetic) or technetium-99m, and coloaded with paramagnetic gadolinium allowing multimodality SPECT and MR imaging and radionuclide therapy with one single agent. METHODS: Diethylenetriaminepentaacetic acid bisoctadecylamide (an amphiphilic molecule with a chelating group suitable for labeling with radionuclides) and gadoliniumacetylacetonate (GdAcAc) (a small lipophilic paramagnetic molecule) were incorporated in liposomes. The liposomes were characterized by measuring their mean size and size distribution, gadolinium content, and radiochemical stability after incubation in human serum at 37 degrees C. The MRI properties (in vitro) were determined by use of relaxivity measurements at 1.5 and 3.0 Tesla in order to evaluate their potency as imaging agents. RESULTS: The liposomes were successfully labeled with holmium-166, resulting in a high labeling efficiency (95% +/- 1%) and radiochemical stability (> 98% after 48 hours of incubation), and coloaded with GdAcAc. Labeling of liposomes with technetium-99m was somewhat less efficient (85% +/- 2%), although their radiochemical stability was sufficient (95% +/- 1% after 6 hours of incubation). MRI measurements showed that the incorporation of GdAcAc had a strong effect on the MRI relaxivity. CONCLUSIONS: The synthesized liposomes allow for multimodality imaging and therapy, which makes these new agents highly attractive for future applications.  相似文献   
1000.
ICS-283 was developed within Intradigm Corporation as a system that is designed for the systemic delivery of therapeutic small interfering (siRNA) to sites of pathological angiogenesis. The non-viral siRNA delivery system is based on synthetic nanoparticles, known as Targe (Intradigm Corporation), which functions as a broad-platform technology to deliver siRNA to specific target cells in diseased tissues. The system is constructed to incorporate different functionalities that address critical needs for successful nucleic acid delivery. The TargeTran synthetic vector is a self-assembling, layered nanoparticle that protects and targets siRNA to specific cell types in pathological tissues. At present, ICS-283 is the only antiangiogenic siRNA delivery system that is designed for intravenous administration to treat angiogenesis-driven diseases.  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