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941.
942.
Endogenous direct-current electric fields (dcEFs) occur in vivo in the form of epithelial transcellular potentials or neuronal field potentials. A variety of cells respond to dcEFs by migrating directionally, and this is termed galvanotaxis. The mechanism by which dcEFs direct cell movement, however, is not yet understood, and the effects on lung cancer cells are entirely unknown. We demonstrated that cultured human lung adenocarcinoma A549 cells migrate toward the cathode in applied dcEFs at 3 V/cm. Fluorescence microscopy showed that both epidermal growth factor receptors (EGFRs) and F-actin are polarized to the cathode. EGFR inhibitors, cetuximab and AG1478, reduced the migration rate and directed motility in dcEFs. Western blots showed that ERK and AKT signaling pathways were prominently promoted by dcEFs. EGFR inhibitors could reduce this promotion but not completely. These data suggest that polarization of EGFRs and the activation of their downstream signals play an important role in the galvanotaxis of A549 cells in dcEFs. 相似文献
943.
This article introduces a multiagent simulation framework for investigating the emergence of niche markets for environmentally innovative products. It clarifies how consumer preferences, business strategy, and government policy interact during market development. The framework allows investigation of the effects of uncertainty and agents' corresponding coping strategies. We describe the model, illustrate how it works when applied to the case of hybrid cars, and analyze results spanning several policy cases and a range of scenarios that make different assumptions about the heterogeneity of agents. Heterogeneity within each agent class strongly influences aggregate outcomes. Innovative firms can create green products in response to or in anticipation of government regulation, but true green niche markets do not emerge unless there are also green consumers. Niche markets do not go mainstream unless scale economies drive costs down to parity with conventional products. Preferred environmental innovation policies change with heterogeneity assumptions. 相似文献
944.
在真空及低压高频脉冲(LHPEF)条件下,结合胰蛋白酶降解猪Hb,利用高效凝胶色谱、Native-PAGE蛋白电泳及紫外扫描来测定其降解效果。结果:在37℃温度下,1.88 V、200 kHz的LHPEF处理猪Hb,电导率为3.45326 ×10^5 μs/cm(对照组为0.645×10^4 μs/cm)。紫外扫描曲线图中的真空LHPEF胰蛋白酶降物中有8个特征吸收峰,而对照组中为6个吸收峰,Native- PAGE蛋白质电泳图中有13个明显色带,而对照组中只有6个色带,高效凝胶色谱图中的特征吸收峰为48个,对照组中7个特征吸收峰。 相似文献
945.
Sprague-Dawley male rats, maintained in a 14:10 h light:dark cycl were exposed for 30 days (starting at 56 days of age) to a 65 kV/m, 60 Hz electric field or to a sham field for 20 h/day beginning at dark onset. Pineal N-acetyltransferase (NAT), hydroxy-indole-o-methyl transferase (HIOMT), and melatonin as well as serum melatonin were assayed. Preliminary data on unexposed animals indicated that samples obtained 4 h into the dark period would reveal either a phase delay or depression in circadian melatonin synthesis and secretion. Exposure to electric fields for 30 days did not alter the expected nighttime increase in pineal NAT, HIOMT, or melatonin. Serum melatonin levels were also increased at night, but the electric field-exposed animals had lower levels than the sham-exposed animals. Concurrent exposure to red light and the electric field or exposure to the electric field at a different time of the day-night period did not reduce melatonin synthesis. These data do not support the hypothesis that chronic electric field exposure reduces pineal melatonin synthesis in young adult male rats. However, serum melatonin levels were reduced by electric field exposure, suggesting the possibility that degradation or tissue uptake of melatonin is stimulated by exposure to electric fields. © 1994 Wiley-Liss, Inc. 相似文献
946.
Ryuji Matsuhashi Yuki Kudoh Yoshikuni Yoshida Hisashi Ishitani Michifumi Yoshioka Kanji Yoshioka 《The International Journal of Life Cycle Assessment》2000,5(5):306-312
This article aims at estimating life cycle CO2 emissions from electric vehicles (EV) and gasoline vehicles (GV), although the estimation in this study is not an LCA according
to ISO14040s. For this purpose, a mathematical tool called the Process-relational model was developed. The Process-relational
model is used for establishing life cycle inventories. The model has a structure which improved the principle of input-output
analysis in econometrics that only one product is generated by one process. This model enabled us to overcome difficulties
of LCA in retracing complicated repercussions among production systems.
Then, life cycle CO2, emissions from electric vehicles (EV) and gasoline vehicles (GV) were estimated with this model. Estimated results indicated
that the manufacture and driving of EV resulted in less CO2 emissions than chose of GV. However, the difference between EV and GV dramatically changed depending on traffic situations.
Namely, the difference became larger as the average velocity of the vehicles became lower. We also compared CO2, emission from manufacturing EV with that from driving EV. The share of manufacture was shown to increase in total CO2, emissions as the average velocity of the EV became higher. In conclusion, we clarified the direction of research and development
of EV and GV for reducing the life cycle CO2. 相似文献
947.
Graciela Ruderman Barry R. Jennings Ian G. Lyle 《International journal of biological macromolecules》1984,6(2):99-102
A study of the transient, electrically induced birefringence of aqueous suspensions of phospholipid vesicles (liposomes) has indicated a rapid and sensitive method of measuring the size and electrical polarizability anisotropy of these entities. 相似文献
948.
Douglas L. Miller 《Bioelectromagnetics》1994,15(5):483-487
Measuring internal induced electric fields in animals with a miniaturized probe involves a potential error related to the difference between the hole conductivity (σh) and the surrounding tissue conductivity (σt). Theory was developed to describe this phenomenon and checked by probe measurements in agar-filled petri dishes. The value measured in the hole is 2σt/(σh + σt) times the actual field in the tissue. For example, a probe hole in muscle, which is filled with blood, could yield a measurement only about 22% of the true value in the muscle. This potential source of error can be mitigated to some extent by not actually cutting a hole, by using a low-conductivity (e.g., 0.2 S/m) coupling medium in the hole, or by ensuring contact between the probe's electrodes and the tissue. © 1994 Wiley-Liss, Inc. 相似文献
949.
950.
Electric fields, which were equivalent to those generated by medical devices, were applied to cultured neuroblastoma cells (mouse and human) to test for morphological damage and to establish damage thresholds. Each of two methods of applying fields permitted flow of electrical current and minimized exposure of cells to electrode-breakdown products. One method consisted of a pair of parallel wires in a Petri dish by which current was delivered within a fixed volume of flowing tissue-culture media. With the other method, the cells were held in a confined geometrical chamber and current was applied via agar bridges. Under a given set of stimulation parameters, damage was found to be variable from cell to cell. By changing the strength of the electric field (frequency and duration of stimulation held constant), thresholds of several V/cm were found above which cell damage could be reliably produced. Depending on the intensity of the field, damage took the form of cell lysis or damage to neurites. Intracellular recordings from the mouse neuroblastoma cells revealed a correlation between a decline in resting transmembrane potential and stimulus intensity. Human neuroblastoma cells were less susceptible to damage than were the mouse neuroblastoma cells, given the same strength of applied electric fields. 相似文献