首页 | 官方网站   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   387篇
  免费   12篇
  国内免费   1篇
工业技术   400篇
  2023年   7篇
  2022年   13篇
  2021年   7篇
  2020年   8篇
  2019年   13篇
  2018年   15篇
  2017年   9篇
  2016年   8篇
  2015年   3篇
  2014年   6篇
  2013年   11篇
  2012年   18篇
  2011年   18篇
  2010年   19篇
  2009年   16篇
  2008年   15篇
  2007年   20篇
  2006年   9篇
  2005年   7篇
  2004年   3篇
  2003年   10篇
  2002年   3篇
  2001年   7篇
  2000年   7篇
  1999年   8篇
  1998年   29篇
  1997年   18篇
  1996年   12篇
  1995年   4篇
  1994年   3篇
  1993年   4篇
  1992年   3篇
  1991年   2篇
  1989年   2篇
  1988年   2篇
  1985年   3篇
  1984年   5篇
  1982年   3篇
  1981年   7篇
  1980年   2篇
  1979年   2篇
  1978年   2篇
  1977年   3篇
  1976年   10篇
  1974年   2篇
  1973年   3篇
  1971年   3篇
  1970年   4篇
  1969年   4篇
  1955年   1篇
排序方式: 共有400条查询结果,搜索用时 15 毫秒
81.
Pneumatic balloon dilatation of the esophagus is one of the current recommended treatment for achalasia. This procedure is associated with risks such as esophageal rupture. Surgery and percutaneous gastrostomy tube placement has been performed in severely affected individuals. The Botulinum Toxin A (BoTxA) is widely used to treat neuromuscular conditions in which spasticity is of concern. We present four cases in which BoTxA was used as an alternative of treatment and in which less invasive modalities were unsuccessful. The patients received a total of 80 units of BoTxA, applied to the submucosa in doses of 20 units in each predetermined quadrants to the lower esophageal sphincter. All patients demonstrated improvement of their symptoms without side effects in this study.  相似文献   
82.
83.
The short-term effect of high fiber intake on fish-oil treatment in 15 free-living, non-insulin-dependent diabetic patients was evaluated by using a controlled, sequential study design. During an 8-wk fish-oil-treatment period when patients received 20 g fish oil/d, the usual daily fiber intake was increased with a 15-g pectin supplement at midpoint. Fish oil alone lowered triacylglycerol and very-low-density-lipoprotein-cholesterol concentrations by 41% and 36%, respectively (both P < 0.01 by the end of the treatment period) with unchanged mean total, low-density-, and high-density-lipoprotein-cholesterol concentrations. When the fiber intake was increased, however, total and low-density-lipoprotein-cholesterol concentrations decreased significantly (P < 0.001 and < 0.05, respectively) with fish-oil treatment. The cholesterol ester fraction of plasma lipids was reduced by 34% when compared with fish oil alone (P < 0.05). The plasma triacylglycerol fraction decreased further by 44% (P < 0.001). Other beneficial effects observed included a 30% decline in the fatty acid fraction (P < 0.002) by end of the treatment period. Diabetic control was maintained during the 12-wk study. In conclusion, a high fiber intake may be beneficial in fish oil-treated diabetic patients.  相似文献   
84.
85.
We have previously demonstrated that stress proteins (SPs) are synthesized in tissues in which malformations are later observed following treatment with the developmental toxicant, retinoic acid (RA), on day 11 of gestation (GD 11). These proteins were not synthesized in tissues which did not present with malformations near partuition. The purpose of the present investigation was to determine if this correlation between early SP synthesis and later malformation was present at other times during gestation. CD-1 strain mice were dosed orally with corn oil or 100 mg/kg body weight RA on GD 10 or 13. Some of the mice in each group were given an intraperitoneal injection of 3H-leucine to label embryonic protein synthesis one hour after dosing with RA. These animals were sacrificed 1.5 hour later, and embryonic protein synthesis was determined by two-dimensional gel electrophoresis followed by autoradiography. Other animals in each group were sacrificed on day 17 of gestation, and fetuses were examined for the presence of malformations. Following treatment with RA on day 10 of gestation, malformations were observed in the forelimbs, the hindlimbs and the tail; heart defects were not observed. SPs of 20-25,000 and 90,000 relative molecular mass (Mr) were synthesized in the forelimb bud and tail; in addition, a second low molecular weight (20-25,000) and a 84,000 Mr SPs were synthesized in forelimb buds. No SPs were synthesized in the hindlimb bud or the heart. Following RA treatment on GD 13, cleft palate was observed in 58% of fetuses; no other malformations were found. Proteins of 34,000, 84,000 and 90,000 Mr were synthesized in craniofacial tissue; SPs were not observed in forelimb bud, hindlimb bud, heart or tail tissues at this time. Therefore, it appears that there may be a correlation between tissue-specific SP synthesis early in organogenesis and the presence of a malformation later in gestation.  相似文献   
86.
The article describes a new method and an installation for determining the strength and crack resistance of brittle tool materials under single impact loading. It also presents data on the metrological characteristics of the installation. The installation is suitable for determining the tensile strength and crack resistance of a number of ceramics, hard alloys of the tungsten-cobalt group, and of polycrystals of superhard materials. The effect of the loading rate on the strength of some materials is demonstrated.Translated from Problemy Prochnosti, No. 7, pp. 33–40, July, 1992.  相似文献   
87.
The just-in-time (JIT) model originated in the manufacturing industry as a way to manage parts inventories process so that specific components could be made available at the appropriate times (that is, "just in time"). This JIT model can be applied to the management of clinical information inventories, so that clinicians can have more immediate access to the most current and relevant information at the time they most need it--when making clinical care decisions. The authors discuss traditional modes of managing clinical information, and then describe how a new, JIT model may be developed and implemented. They describe three modes of clinician-information interactions that a JIT model might employ, the scope of information that may be made available in a JIT model (global information or local, case-specific information), and the challenges posed by the implementation of such an information-access model. Finally, they discuss how JIT information access may change how physicians practice medicine, various ways JIT information may be delivered, and concerns about the trustworthiness of electronically published and accessed information resources.  相似文献   
88.
89.
As the Internet of things (IoT) technology is evolving, distributed solar energy resources can be operated, monitored, and controlled remotely. The design of an IoT based solar energy system for smart irrigation is essential for regions around the world, which face water scarcity and power shortage. Thus, such a system is designed in this paper. The proposed system utilizes a single board system-on-a-chip controller (the controller hereafter), which has built-in WiFi connectivity, and connections to a solar cell to provide the required operating power. The controller reads the field soil moisture, humidity, and temperature sensors, and outputs appropriate actuation command signals to operate irrigation pumps. The controller also monitors the underground water level, which is essential to prevent the pump motors from burning due to the level in the water well. The proposed system has three modes of operations, i.e. the local control mode, mobile monitoring-control mode, and fuzzy logic-based control mode. For the purpose of the proposed system validation, a prototype was designed, built, and tested.  相似文献   
90.
The contribution of acetoacetate (AcAc), β-hydroxybutyrate (βOHB), lactate and glucose to pulmonary surfactant lipid synthesis in three-to five-day-old rats was measured. Minced lung tissue was incubated with3H2O and [3-14C]AcAc, [3-14C]βOHB, [U-14C]lactate or [U-14C]glucose, and the radioactivity incorporated into surfactant lipids was measured. When expressed as nmol of substrate incorporated/g lung tissue per four hr, lactate was incorporated more rapidly than other substrates into total surfactant lipids and phosphatidylcholine (PC). There was no difference in the rates of incorporation of lactate, AcAc or glucose into disaturated PC (DSPC). Substrates other than glucose were incorporated almost exclusively into fatty acids, whereas 60–80% of glucose incorporated into surfactant phospholipids was found in fatty acids, with the remaining in glyceride-glycerol. When expressed as nmol acetyl units incorporated/g lung tissue per four hr, the rates of AcAc, lactate and glucose incorporation into total surfactant fatty acids were comparable. Glucose incorporation into DSPC and PC was greater than that of AcAc and lactate. When glucose was the only exogenous substrate added to the incubation medium, it contributed 37% of total surfactant fatty acids synthesized de novo. In the presence of other substrates, the contribution of glucose to de novo fatty acid synthesis dropped to 14–20%. In the presence of unlabeled glucose,14C-labeled AcAc, lactate and βOHB contributed 52%, 40% and 19%, respectively, of the total fatty acids synthesized de novo. The rate of βOHB incorporation into surfactant lipids was only about 50% that of other substrates and was accompanied by low activity of β-hydroxybutyrate dehydrogenase measured for newborn lung. These results demonstrate that AcAc and lactate are important precursors for surfactant lipids in neonatal rat lung.  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-23

京公网安备 11010802026262号